Methods and apparatus for controlling and making link bundle advertisements to support routing decisions

ABSTRACT

Methods and apparatus relating to the use of aggregated links, e.g., links in a bundle, are described. A normal link metric and a limited operation mode link metric a determined for a link bundle, the normal link metric having a lower value than the limited operational mode link metric. The status of links in a link bundle are monitored. Based on the number of currently operational links in a link bundle and a switching threshold, a decision is made whether to advertise the normal link metric, advertise the limited operation mode threshold or refrain from advertising any link metric. The use of the limited operation link metric facilitates the use of a partially failed link bundle providing an alternative routing path in the network that would not otherwise be available.

RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 16/740,478 filed Jan. 12, 2020 which published as U.S. patentpublication US 2020-0153727 A1 on May 14, 2020, which is a continuationof U.S. patent application Ser. No. 16/130,715 filed Sep. 13, 2018 whichissued as U.S. Pat. No. 10,536,366 on Jan. 14, 2020, each of thepreceding patent applications and publications being hereby expresslyincorporated by reference in their entirety.

FIELD

The present application relates to communications methods and, moreparticularly, to methods and apparatus for determining and communicatinglink and/or link bundle information which can be used for making routingdecisions.

BACKGROUND

Link metrics, often referred to as link weights, are sometimesadvertised and used in a communications network by devices trying tomake routing decisions with regard to which path to use. For example, inthe case of shortest path first routing, link metrics indicative of pathlength are advertised and routing decisions are made based on theadvertised link metrics, e.g., with the links which result in the lowestcumulative link metric between a source device and destination devicebeing selected for inclusion in a route between the source anddestination device. In other cases where the link metrics represent costmetrics, the advertised link metrics are normally indicative of a costassociated with a link. In a cost based approach to routing a devicewill normally select the lowest cost path as indicated by selecting apath with the lowest overall cost as indicated by the cumulative sum ofthe link metrics of each link in the selected path.

Link aggregation allows multiple links, e.g., Ethernet links, into asingle logical link between two networked devices. An aggregation oflinks is often referred to as a bundle. For purposes of advertising alink metric, the logical link is treated as a single link even though itrepresents a bundle of individual links. Accordingly, a single linkmetric is normally advertised for a bundle.

Link Aggregation Control Protocol (LACP) is an IEEE standard defined inIEEE 802.3ad. LACP lets devices send Link Aggregation Control ProtocolData Units (LACPDUs) to each other to establish a link aggregationconnection. The metric used to facilitate routing decisions is oftencommunicated as a Link Aggregation Control Protocol Data unit.

A useful feature of LACP is that when one member link stops sendingLACPDUs (if the cable is unplugged, for example), it is removed from thelink aggregation group (LAG). This helps to minimize packet loss.

In the case of link bundles, it is often possible to configure a deviceto stop advertising a metric for a link bundle if the number ofoperational links in the bundle falls below a configured number oflinks, e.g., a number of links expected to be needed to support a normalor anticipated traffic load. Once a metric for the bundle ceases to beadvertised, the bundle will normally be removed from the set of linkswhich are considered by devices for routing purposes in accordance withthe link protocol being used.

Removing a bundle which can no longer handle the expected normal trafficload reduces the risk of packet loss, e.g., due to overloading of abundle which is suffering from one or more faulty connections or linkswhich reduce its capacity. Networks are often designed with sufficientredundancy that if one link bundle fails another, e.g., redundant, linkbundle will be able to handle the load.

While the removal of one bundle from a network from one or more linkfailures in the links which form the bundle may not have significantimpact on a network, the failure of multiple bundles may result in aportion of a network being coming isolated.

In view of the above discussion it should be appreciated that there is aneed for methods and/or apparatus which would allow a bundle to beremoved from being used when a functional alternative bundle can serveas an alternative path for the full normal traffic flow but which wouldleave the bundle as an available link, albeit one that might not be ableto support the full normal traffic flow, in cases where failure to usethe one or more functional links in the bundle would result in a portionof a network becoming isolated due to the lack of a good alternativelink or bundle.

SUMMARY

Methods and apparatus relating to the use of aggregated links, e.g.,links in a bundle, are described. In accordance with various featureswhen the number of links in a bundle drops below a predetermined numberof links, e.g., a number of links which can and sometimes is set on aper bundle basis taking into consideration the number of functionallinks required to support the expected normal bundle traffic load of thebundle, a switch is made between advertising a normal bundle link metricto advertising a limited operation mode link bundle metric. In someembodiments, the predetermined number or links is 1 greater than thelimited operation mode number of links. In some cases the limitedoperation mode link bundle metric is set to the maximum possible linkmetric value. While in some embodiments for normal operation the linkmetric is a metric based on path length or cost, in the case of limitedoperation mode the metric is one which is intended to discourage use ofthe bundle as a link. When the link metric value is set to the maximumpossible value the faulty link bundle becomes a link of last resortsince it will be perceived as the longest, most costly, or otherwiseundesirable link in any set of possible links being considered forrouting purposes since the link metric is set to the maximum possiblevalue. In other embodiments the link metric advertised for a link inlimited operation mode is a multiple of the normal link metric for thelink bundle. Thus the link bundle will be less desirable from a routingperspective discoursing use of the bundle below what would be its normallevel of use. In some embodiments the limited operation mode metric fora bundle is determined based on the number of links which remainavailable for use with the metric increasing in value as the number oflinks decreased from the threshold number used to trigger limited linkmode operation.

While adverting a large link metric for a link bundle can significantlydecrease the likelihood that a bundle will be used and in some casesmakes the bundle a link of last resort, advertising a limited mode linkmetric for a faulty bundle unable to support its normal traffic loadkeeps the remaining links in the bundle available for use and can avoida network segment from becoming isolated as might be the case ifmultiple partial bundle failures triggered nodes to stop advertisinglink metrics making the links of the bundles unavailable.

While in various embodiments the methods and apparatus are used in thecontext of Ethernet link bundles and LACP, the methods and apparatus canbe used in wide range of communications networks and with various typeof communications links which may be aggregated into a bundle and whichcan thus serve as a logical link between two network nodes.

An exemplary method of operating a first node in a communicationsnetwork, in accordance with some embodiments, comprises: determining anormal link bundle metric for a first link bundle including a pluralityof communications links between a first network node and a secondnetwork node; determining a limited operation mode link bundle metricfor the first link bundle; and making a first link bundle metricadvertising decision, said first link bundle metric advertising decisionbeing a decision to: i) advertise the normal link bundle metric for thefirst link bundle; ii) advertise the limited operation mode link bundlemetric for the first link bundle; or iii) perform no advertising of alink bundle metric for the first link bundle; and taking an advertisingaction in accordance with the determined first link bundle metricadvertising decision, said advertising action including operating thefirst node to: i) advertise the normal link bundle metric for the firstlink bundle, ii) advertise the limited operation mode link bundle metricfor the first link bundle or iii) control the first node to refrain fromadvertising a link bundle metric for the first link bundle.

While various features discussed in the summary are used in someembodiments it should be appreciated that not all features are requiredor necessary for all embodiments and the mention of features in thesummary should in no way be interpreted as implying that the feature isnecessary or critical for all embodiments.

Numerous additional feature and embodiments are described in thedetailed description which follows.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates an exemplary communications system, implemented inaccordance with an exemplary embodiment, during failure free operationin which each of the routers are advertising normal link metrics.

FIG. 2 illustrates the exemplary communications system of FIG. 1 inwhich a first failure has occurred and a limited operation mode linkmetric is being advertised corresponding to link bundle 1.

FIG. 3 illustrates the exemplary communications system of FIG. 1 , inwhich a first failure has occurred and a limited operation mode linkmetric is being advertised corresponding to link bundle 1; and in whicha second failure has occurred and link metrics are not being advertisedfor link bundles 2, 3, and 5.

FIG. 4 is a more detailed representation of the FIG. 1 example, whichillustrates routing controllers in each of the routers, and furtherillustrates line cards in each of the routers.

FIG. 5 is a more detailed representation of FIG. 2 example, whichillustrates that line cards (line card 1 and line card 2) in router 1have failed resulting in the first failure and the advertising of thelimited operation mode link metric for the logical link corresponding tolink bundle 1.

FIG. 6 is a more detailed representation of FIG. 3 example, whichillustrates that line cards (line card 1 and line card 2) in router 1have failed resulting in the first failure and the advertising of thelimited operation mode link metric for the logical link corresponding tolink bundle 1; and further illustrates the each of the line cards inrouter 2 are failing, resulting in 0 good links from router 2, and as aresult link metrics are not advertised corresponding to link bundles 2,3 and 5.

FIG. 7A is a first part of a flowchart of an exemplary method ofoperating a node, e.g., a router, in accordance with an exemplaryembodiment.

FIG. 7B is a second part of a flowchart of an exemplary method ofoperating a node, e.g., a router, in accordance with an exemplaryembodiment.

FIG. 7C is a third part of a flowchart of an exemplary method ofoperating a node, e.g., a router, in accordance with an exemplaryembodiment.

FIG. 7B is a fourth part of a flowchart of an exemplary method ofoperating a node, e.g., a router, in accordance with an exemplaryembodiment.

FIG. 7 comprises the combination of FIG. 7A, FIG. 7B, FIG. 7C and FIG.7D.

FIG. 8 is a drawing of a table illustrating exemplary link bundleinformation corresponding to the example of FIG. 1 and FIG. 4 .

FIG. 9 is a drawing of a table illustrating exemplary link bundleinformation corresponding to the example of FIG. 2 and FIG. 5 .

FIG. 10 is a drawing of a table illustrating exemplary link bundleinformation corresponding to the example of FIG. 3 and FIG. 6 .

FIG. 11A is a first part of a flowchart of an exemplary method ofoperating a first node, e.g., a router, in accordance with an exemplaryembodiment.

FIG. 11B is a second part of a flowchart of an exemplary method ofoperating a first node, e.g., a router, in accordance with an exemplaryembodiment.

FIG. 11C is a third part of a flowchart of an exemplary method ofoperating a node, e.g., a router, in accordance with an exemplaryembodiment.

FIG. 11 comprises the combination of FIG. 11A, FIG. 11B, and FIG. 11C.

FIG. 12 is a drawing of an exemplary node, e.g., a router, in accordancewith an exemplary embodiment.

FIG. 13A is a drawing of a first part of an exemplary assembly ofcomponents which may be included in an exemplary communications device,e.g., a router, in accordance with an exemplary embodiment.

FIG. 13B is a drawing of a second part of an exemplary assembly ofcomponents which may be included in an exemplary communications device,e.g., a router, in accordance with an exemplary embodiment.

FIG. 13C is a drawing of a third part of an exemplary assembly ofcomponents which may be included in an exemplary communications device,e.g., a router, in accordance with an exemplary embodiment.

FIG. 13 comprises the combination of FIG. 13A, FIG. 13 B and FIG. 13C.

FIG. 14 illustrates examples of an exemplary selected communicationspaths corresponding to the example of FIG. 1 and FIG. 4 .

FIG. 15 illustrates an example of an exemplary selected communicationspaths corresponding to the example of FIG. 2 and FIG. 5 .

FIG. 16 illustrates an example of an exemplary selected communicationspaths corresponding to the example of FIG. 3 and FIG. 6 .

FIG. 17 is a drawing of a table illustrating exemplary bundleinformation for an exemplary link bundle, wherein the limited operationmode link metric for the link bundle is a maximum link weight value, inaccordance with an exemplary embodiment.

FIG. 18 is a drawing of a table illustrating exemplary bundleinformation for an exemplary first link bundle, wherein the limitedoperation mode link metric for the first link bundle is a multiple,e.g., 4X, of the normal link metric for the first link bundle, inaccordance with an exemplary embodiment.

FIG. 19 is a drawing of a table illustrating exemplary bundleinformation for an exemplary second link bundle, wherein the limitedoperation mode link metric for the second link bundle is multiple, e.g.,4X, of the normal link metric for the second link bundle, in accordancewith an exemplary embodiment.

FIG. 20 is a drawing of a table illustrating exemplary bundleinformation for an exemplary link bundle, wherein the limited operationmode link metric for the link bundle is a function of the determinednumber of operational links in the link bundle, in accordance with anexemplary embodiment.

FIG. 21A is a drawing of a first part of an exemplary assembly ofcomponents which may be included in an exemplary communications device,e.g., a router, in accordance with an exemplary embodiment.

FIG. 21B is a drawing of a second part of an exemplary assembly ofcomponents which may be included in an exemplary communications device,e.g., a router, in accordance with an exemplary embodiment.

FIG. 21C is a drawing of a third part of an exemplary assembly ofcomponents which may be included in an exemplary communications device,e.g., a router, in accordance with an exemplary embodiment.

FIG. 21 comprises the combination of FIG. 21A, FIG. 21B and FIG. 21C.

DETAILED DESCRIPTION

FIG. 1 illustrates an exemplary communications system 100 implemented inaccordance with an exemplary embodiment. Communications system 100includes a plurality of routers (router 1 102, router 2 104, router 3106, router 4 108, router 5 110, router 6 112), and a plurality ofcustomer premises equipment (CPE)/user devices (CPE/user device 1 114,CPE/user device 2 116, CPE/user device 3 118, CPE/user device 4 120),coupled together as shown in FIG. 1 . Router 1 102 and router 104 arepart of a core network 122. Router 3 and router 4 are part of a backbonenetwork 124. Router 5 110 and router 6 112 are part of stub network 126.

Router 1 102 is coupled to router 3 106 via link bundle B1 128. Router 2104 is coupled to router 4 108 via link bundle B2 130. Router 1 102 iscoupled to router 2 104 via link bundle B3 132. Router 1 102 is coupledto router 5 110 via link bundle B4 134. Router 2 104 is coupled torouter 6 112 via link bundle B5 136. Router 3 106 is coupled to router 4108 via link bundle B6 138. Router 5 110 is coupled to router 6 112 vialink bundle B7 140.

In FIG. 1 , each line in an illustrated link bundle (B1, B2, B3, B4, B5,B6) represents multiple physical connections, e.g., one line in linkbundle B1 128 represents 3 physical connections between router 1 102 androuter 3 106.

CPE/user device 1 114 is coupled to router 3 106 via link 142. CPE/userdevice 2 116 is coupled to router 4 108 via link 144. CPE/user device 3118 is coupled to router 5 110 via link 146. CPE/user device 4 120 iscoupled to router 6 108 via link 148.

The example of FIG. 1 corresponds to failure free operation in whicheach of the routers are advertising normal link metrics (NLM).Corresponding to each of the link bundles (B1 128, B2 130, B3 132, B4134, B5 136, B6 138, B7 140), the following normal link metric valuesare advertised (NLM=2, NLM=2, NLM=1, NLM=2, NLM=2, NLM=1, NLM=1). Inaddition, the normal link metric values for links (142, 144, 146, 148)are (NLM=1, NLM=1, NLM=1, NLM=1), respectively.

FIG. 2 is a drawing 200 illustrating the exemplary communications systemof FIG. 1 in which a first failure has occurred, as indicated by the Xs202, and a limited operation mode link metric (LOMLM), with a valueequal to 9, is now being advertised corresponding to link bundle B1 128.

FIG. 3 is a drawing 300 illustrating exemplary communications system ofFIG. 1 , in which a first failure has occurred, as indicated by the Xs202, and a limited operation mode link metric (LOMLM), with a valueequal to 9, is now being advertised corresponding to link bundle B1 128.The example of FIG. 3 further illustrates that a second failure hasoccurred, which is router 2 104 has failed, as indicated by the large X302 on router 104, and router 2 104 does not have any good links, and asa result link metrics are not being advertised, e.g., from router 2 104,for link bundles B2 130, B3 132, and B5 136. Assuming that both sideshave noticed the failure on each link for link bundle B2 130, neitherrouter 2 104 nor router 4 108 will advertise a link metric for linkbundle B2 130. Assuming that both sides have noticed the failure on eachlink for link bundle B3 132, neither router 2 104 nor router 1 102 willadvertise a link metric for link bundle B3 132. Assuming that both sideshave noticed the failure on each link for link bundle B5 136, neitherrouter 2 104 nor router 6 112 will advertise a link metric for linkbundle B5 136.

FIG. 4 is drawing 400 which is a more detailed representation of thesystem 100 of FIG. 1 . Drawing 400 illustrates that each of the routers(router 1 102, router 2 104, router 3 106, router 4 108, router 5 110,router 6 112) includes a routing controller (RC 402, RC 422, RC 442, RC458, RC 472, RC 488), respectively. Each router (102, 104, 106, 108,110, 112) further includes a plurality of line cards (LCs).

Router 1 102 includes LC1 404, LC2 406, LC3 408, LC4 410, LC5 412, LC6414, LC7 416, LC8 418, LC9 420. Router 2 104 includes LC1 424, LC2 426,LC3 428, LC4 430, LC5 432, LC6 434, LC7 436, LC8 438, LC9 430.

Router 3 106 includes LC1 444, LC2 446, LC3 448, LC4 450, LC5 452, LC6454, LC7 456. Router 4 108 includes LC1 460, LC2 462, LC3 464, LC4 466,LC5 468, LC6 470, LC7 472.

Router 5 110 includes LC1 474, LC2 476, LC3 478, LC4 480, LC5 482, LC6484, LC7 486. Router 6 112 includes LC1 489, LC2 490, LC3 491, LC4 492,LC5 493, LC6 494, LC7 495.

In this example, each bundle (B1, B2, B3, B4, B5, B6, B7), includes 9physical connections, between two routers, with there being 3connections per pair of line cards. For example, corresponding to bundleB1 128, there are three physical connections between LC1 404 of router 1102 and LC4 450 of router 3 106; there are three physical connectionsbetween LC2 406 of router 1 102 and LC5 452 of router 3 106; and thereare three physical connections between LC3 408 of router 1 102 and LC6454 of router 3 106. Although there are 9 physical connections betweenrouter 1 102 and router 3 106, which are part of link bundle B 128, asingle metric, which in this example is NLM=2, is advertised for thelink bundle B1 128.

FIG. 5 is drawing 500 which is a more detailed representation of FIG. 2example, which includes the routing controllers and line cards asalready shown and described with respect to FIG. 4 . Drawing 500 of FIG.5 further illustrates that line cards (line card 1 (LC1) 404, and linecard 2 (LC2) 406 in router 1 102 have failed, as indicted by the Xs 502on LC1 404 and LC2 406, resulting in the first failure 202 and theadvertising of the limited operation mode link metric (LOMLM)=9 for thelogical link corresponding to link bundle B1 128.

In this exemplary embodiment, if the number of good links in link bundleB1 is in the range {4 . . . 9}, then the normal link metric (NLM), withvalue=2 is advertised; however, if the number of good links in the linkbundle Blis in the range 11 . . . 31 then the limited operation modelink metric (LOMLM), with value=9 is advertised; and if no links in thelink bundle B1 are good then a link metric is not advertised for thelink bundle B1. In this example, 3 links are good, which correspond toline card LC3 408; therefore router 1 102 advertised LOMLM=9corresponding to link bundle B1 128.

FIG. 6 is a drawing 600 which is more detailed representation of FIG. 3example, which includes the routing controllers and line cards asalready shown and described with respect to FIG. 4 and FIG. 5 . Drawing600 of FIG. 6 further illustrates that line cards line card 1 (LC1) 404,and line card 2 (LC2) 406 in router 1 102 have failed, as indicted bythe Xs 502 on LC1 404 and LC2 406, resulting in the first failure 202and the advertising of the limited operation mode link metric (LOMLM)=9for the logical link corresponding to link bundle B1 128. Drawing 600further illustrates that router 2 104 is experiencing a major failure,as indicated by large X 302 over router 2 104. Drawing 600 of FIG. 6further illustrates the each of the line cards (LC 1 424, LC2 426, LC3428, LC4 430, LC5 432, LC6 434, LC7 436, LC8 438, LC9 440) in router 2104 are failing, as indicated by small Xs 602 on each of LCs (424, 426,428, 430, 432, 434, 436, 438, 440), resulting in 0 good links fromrouter 2 302, and as a result link metrics are not advertisedcorresponding to link bundles B2 130, B3 132 and B5 136.

FIG. 7 , comprising the combination of FIG. 7A, FIG. 7B, FIG. 7C andFIG. 7D, is a flowchart 700 of an exemplary method of operating a node,e.g., a router, in a communications network in accordance with anexemplary embodiment. The node implementing the method of flowchart 700is, e.g., one of the routers (router 1 102, router 2 104, router 3 106,router 4 108, router 5 106, router 6 106) of system 100 of FIGS. 1-6 .

Operation of the exemplary method starts in step 702, in which the nodeis powered on and initialized. Operation proceeds from start step 702 tostep 704. In step 704 the node determines normal operation mode linkbundle metrics, e.g., one per link bundle. In some embodiments, step 704includes step 706 in which the node receives input indicating a normallink metric for each link bundle. In some embodiments, step 704 includesstep 708 in which the node automatically generates, on a per link bundlebasis, a normal link metric for each link bundle. Operation proceedsfrom step 704 to step 710.

In step 710 the node stores the normal operation link metric for eachlink bundle in memory. Operation proceeds from step 710 to step 712.

In step 712 the node received limited operation threshold information,on a per link bundle basis, e.g., a value, e.g., a threshold value,indicating a failed number of links in a bundle which is used to triggerlimited operation mode for a link bundle corresponding to the indicatedthreshold value or a value, e.g., a threshold value, indicating a numberof good links in a link bundle which is the upper number of good linksfor limited operation mode. In some embodiments, the limited operationthreshold information for a link bundle is a limited operation thresholdnumber for the link bundle, which indicates the upper limit number ofoperational links for which the node will be operated in limitedoperation mode with regard to the link bundle, and if the number ofoperational links is above the limited operation threshold number thenode will operate in normal mode with regard to the link bundle. In someembodiments, the total number of links in the link bundle is known tothe node, and therefore a limited operation threshold number, whichindicates the upper limit number of operational links for which the nodewill be operated in limited operation mode with regard to the linkbundle, also indicates a failed number of links in the bundle used totrigger limited operation mode for the link bundle. Operation proceedsfrom step 712 to step 714, in which the node stores the limitedoperation threshold information in memory. Operation proceeds from step714, via connecting node A 716, to step 718.

In step 718 the node determines limited operation mode link bundlemetrics, e.g., one per link bundle, to be advertised during limitedoperation mode of bundle operation. In some embodiments, step 718includes step 720 in which the node receives input, e.g., a max bundlelink weight, on a per link bundle basis, indicating a limited operationmode link metric (LOMLM) value for each link bundle. In someembodiments, step 718 includes step 722 in which the node automaticallygenerates, on a per link bundle basis, a limited operation mode linkmetric for each link bundle. In some embodiments, step 722 includes step724 in which the node multiplies a normal link metric for a link bundleby a multiplier factor, e.g., a multiplier factor greater than 1, togenerate a limited operation mode link metric for the link bundle.Operation proceeds from step 718 to step 726.

In step 726 the node stores the limited operation mode link metrics inmemory, e.g., on a per link bundle basis. Step 726 includes step 728 inwhich the node stores the limited operation mode link metric for thefirst link bundle. In some embodiments, step 726 includes step 730 inwhich the node stores the limited operation mode link metric for the Nthlink bundle. Operation proceeds from step 726 to step 732.

In step 732 the node monitors the status of links in each bundle. Step732 includes step 734 and may include step 736 and step 738, dependingupon the number of bundles. In step 734 the node determines the numberof operational links in the first link bundle. In step 736 the nodedetermines the number of operational links in the second link bundle. Instep 738 the node determines the number of operational links in the Nthlink bundle. Operation proceeds from step 732, via connecting node B740, to step 741, e.g., for each bundle being monitored. Thus theflowchart portions of FIG. 7C and FIG. 7D may be, and sometimes are,executed, e.g., in parallel, for each of the N bundles being monitored.

In step 741 the node determines if the determined number of operationallinks in the link bundle, e.g., from one of steps 734, 736, . . . , 738,is an initially determined value for the link bundle. If the determinednumber of operational links for the link bundle is an initiallydetermined value, e.g., a value obtained from a first pass of one ofsteps 734, 736, . . . , 738, then operation proceeds from step 741 tostep 743; otherwise, operation proceeds from step 741 to step 742.

In step 743 the node stores the determined number of operational links,e.g., good links, for the link bundle in memory as the number ofcurrently operational links for the link bundle. Operation proceeds fromstep 743 to step 750.

In step 742, the node determines if the determined number of operationallinks in the link bundle has changed, e.g., where the link bundle is oneof N link bundles being monitored, e.g., the 1st link bundle, secondlink bundle, . . . , or Nth link bundle. In some embodiments, in step742 the node compares the value determined in the most recent iterationof one of steps 734, 736, . . . , 738, to the value stored in memory forthe number of currently operational links for the link bundle, whichrepresents the value from the second most recent iteration of one ofsteps 734, 736, . . . , and 738. If the determined number of operationallinks has not changed, e.g., the status of the link bundle has notchanged, then operation proceeds from step 742 to step 744 in which thenode leaves the number of currently operation link in memory for each ofthe bundles unchanged. Operation proceeds from step 744, via connectingnode E 746, to step 732. However, if the determined number ofoperational links in the link bundle has changed, e.g., the status ofthe link bundle has changed, then operation proceeds from step 742 tostep 748 in which the node updates the number of currently operationallinks in memory for the bundle to the most recently determined number ofoperational links in the bundle. Operation proceeds from step 748 tostep 750.

In step 750 the node determines if the current number of operationallinks, e.g., good links, in the bundle is above the limited operationthreshold number for the link bundle. In one example, there are 9 linksin a link bundle and the limited operation threshold number is three. Insome embodiments, the limited operation threshold number is a functionof the number of links in the link bundle, e.g., a rounded integer whichis a fractional percentage of the number of links in the link bundle,said fractional percentage being less than ½. If the determination thatthe number of good links is above, the limited operation thresholdnumber, then operation proceeds from step 750 to step 754, in which thenode sets the current mode of operation for the link bundle, e.g. inmemory, to normal operation mode. Operation proceeds from step 754 tostep 756 in which the node sets an advertise link metric indicator toadvertise, e.g., sets the advertise link metric indicator to indicateyes. In some embodiments an advertise link metric indicator value of 1indicates yes which signifies advertise. Operation proceeds from step756 to step 758. In step 758 the node advertises the normal operationlink metric for the link bundle. In some embodiments, step 758 includesoperating a transmitter in the node to transmit the normal link metricfor the link bundle. Operation proceeds from step 758, via connectingnode E 746, to step 732.

Returning to step 750, in step 750 if the determination is that thenumber of operational links, e.g., good links, in the link bundle is notabove the limited operation threshold number, then operation proceedsfrom step 750, via connecting node D 752, to step 760.

In step 760 the node determines if there are any links in the linkbundle which are operational, e.g., is the number of operational linksin the link bundle greater than zero. If the determination of step 760is that there are no operational links in the link bundle, thenoperation proceeds from step 760 to step 762, in which the node sets theadvertise link metric indicator to no, e.g., indicating that there willbe no advertisement for this link bundle. In some embodiments anadvertise link metric indicator value of 0 indicates no which signifiesdo not advertise. In various embodiments, when the advertise link metricindicator corresponding to a link bundle is set to no, the node isoperated to control the node to refrain from transmitting a link metriccorresponding to the link bundle. Operation proceeds from step 762, viaconnecting node B 740, to step 742, where the status of this link bundleis checked at a later point in time.

Returning to step 760, if the determination of step 760 is that there isat least one operational link in the link bundle, then operationproceeds from step 760 to step 764. In step 764 the node determines thatthe number of operational links in the link bundle is a number whichtriggers limited operation mode with regard to operating the linkbundle. In one example, there are 9 links in a link bundle, and ifdetermined that the number of operational links in the link bundle isany of: 1, 2 or 3, then limited operational mode is triggered. Operationproceeds from step 764 to step 766.

In step 766 the node sets the current mode of the link bundle to limitedoperation mode, e.g., sets an indicator in memory to indicate limitedoperation mode. Operation proceeds from step 766 to step 768.

In step 768 the node set the advertise link metric indicator to yes,indicating that a link metric will be advertised for the link bundle.Operation proceeds from step 768 to step 770, in which the nodeadvertises the limited operation mode link metric (LOMLM) for the linkbundle. In some embodiments, step 770 includes operating a transmitterin the node to transmit the limited operation mode link metric for thelink bundle. Operation proceeds from step 770, via connecting node B749, to step 742, where the status of this link bundle is checked at alater point in time.

FIG. 8 is a drawing of a table 800 illustrating exemplary link bundleinformation corresponding to the example of FIG. 1 and FIG. 4 . Firstcolumn 802 includes link bundle number information used to identify eachof the links bundles. Second column 804 includes a normal link metric(NLM) value for each of the link bundles. Third column 806 includes alimited operation threshold value for each of the link bundles. Fourthcolumn 808 includes a limited operation mode link metric (LOMLM) valuefor each of the link bundles. Fifth column 810 lists a current mode foreach of the link bundles. Sixth column 812 lists the number of operationlinks for each of the link bundles, and seventh column 814 lists whetheror not a link metric is advertised, e.g., whether or not one of NLM orLOMLM, is advertised, for the link bundle.

First row 816 indicates that link bundle B1 has a NLM=2, a limitedoperation threshold=3, a LOMLM=9, is in normal mode, currently has 9operational links, and the advertising link metric is set to yes. Theinformation in first row 816 is, e.g., included in router 1 102 androuter 3 106. Each of router 1 102 and router 3 106 advertise NLM=2 forlink bundle B1 128.

Second row 818 indicates that link bundle B2 has a NLM=2, a limitedoperation threshold=3, a LOMLM=9, is in normal mode, currently has 9operational links, and the advertising link metric is set to yes. Theinformation in second row 818 is, e.g., included in router 2 104 androuter 4 108. Each of router 2 104 and router 4 108 advertise NLM=2 forlink bundle B2 130.

Third row 820 indicates that link bundle B3 has a NLM=1, a limitedoperation threshold=3, a LOMLM=9, is in normal mode, currently has 9operational links, and the advertising link metric is set to yes. Theinformation in third row 820 is, e.g., included in router 1 102 androuter 2 104. Each of router 1 102 and router 2 104 advertise NLM=1 forlink bundle B3 132.

Fourth row 822 indicates that link bundle B4 has a NLM=2, a limitedoperation threshold=3, a LOMLM=9, is in normal mode, currently has 9operational links, and the advertising link metric is set to yes. Theinformation in fourth row 822 is, e.g., included in router 1 102 androuter 5 110. Each of router 1 102 and router 5 110 advertise NLM=2 forlink bundle B4 134.

Fifth row 824 indicates that link bundle B5 has a NLM=2, a limitedoperation threshold=3, a LOMLM=9, is in normal mode, currently has 9operational links, and the advertising link metric is set to yes. Theinformation in fifth row 824 is, e.g., included in router 2 104 androuter 6 112. Each of router 2 104 and router 6 112 advertise NLM=2 forlink bundle B5 136.

Sixth row 826 indicates that link bundle B6 has a NLM=1, a limitedoperation threshold=3, a LOMLM=9, is in normal mode, currently has 9operational links, and the advertising link metric is set to yes. Theinformation in sixth row 826 is, e.g., included in router 3 106 androuter 4 108. Each of router 3 106 and router 4 108 advertise NLM=1 forlink bundle B6 138.

Seventh row 828 indicates that link bundle B7 has a NLM=1, a limitedoperation threshold=3, a LOMLM=9, is in normal mode, currently has 9operational links, and the advertising link metric is set to yes. Theinformation in seventh row 828 is, e.g., included in router 5 110 androuter 6 112. Each of router 5 110 and router 6 112 advertise NLM=1 forlink bundle B7 140.

FIG. 9 is a drawing of a table 900 illustrating exemplary link bundleinformation corresponding to the example of FIG. 2 and FIG. 5 . Firstcolumn 902 includes link bundle number information used to identify eachof the links bundles. Second column 904 includes a normal link metric(NLM) value for each of the link bundles. Third column 906 includes alimited operation threshold value for each of the link bundles. Fourthcolumn 908 includes a limited operation mode link metric (LOMLM) valuefor each of the link bundles. Fifth column 910 lists a current mode foreach of the link bundles. Sixth column 912 lists the number of operationlinks for each of the link bundles, and seventh column 914 lists whetheror not a link metric is advertised, e.g., whether or not one of NLM orLOMLM, is advertised, for the link bundle.

First row 916 indicates that link bundle B has a NLM=2, a limitedoperation threshold=3, a LOMLM=9, is in limited operation mode,currently has 3 operational links, and the advertising link metric isset to yes. The information in first row 916 is, e.g., included inrouter 1 102 and router 3 106. Each of router 1 102 and router 3 106advertise LOMLM=9 for link bundle B1 128.

Second row 918 indicates that link bundle B2 has a NLM=2, a limitedoperation threshold=3, a LOMLM=9, is in normal mode, currently has 9operational links, and the advertising link metric is set to yes. Theinformation in second row 918 is, e.g., included in router 2 104 androuter 4 108. Each of router 2 104 and router 4 108 advertise NLM=2 forlink bundle B2 130.

Third row 920 indicates that link bundle B3 has a NLM=1, a limitedoperation threshold=3, a LOMLM=9, is in normal mode, currently has 9operational links, and the advertising link metric is set to yes. Theinformation in third row 920 is, e.g., included in router 1 102 androuter 2 104. Each of router 1 102 and router 2 104 advertise NLM=1 forlink bundle B3 132.

Fourth row 922 indicates that link bundle B4 has a NLM=2, a limitedoperation threshold=3, a LOMLM=9, is in normal mode, currently has 9operational links, and the advertising link metric is set to yes. Theinformation in fourth row 922 is, e.g., included in router 1 102 androuter 5 110. Each of router 1 102 and router 5 110 advertise NLM=2 forlink bundle B4 134.

Fifth row 924 indicates that link bundle B5 has a NLM=2, a limitedoperation threshold=3, a LOMLM=9, is in normal mode, currently has 9operational links, and the advertising link metric is set to yes. Theinformation in fifth row 924 is, e.g., included in router 2 104 androuter 6 112. Each of router 2 104 and router 6 112 advertise NLM=2 forlink bundle B5 136.

Sixth row 926 indicates that link bundle B6: has a NLM=1, a limitedoperation threshold=3, a LOMLM=9, is in normal mode, currently has 9operational links, and the advertising link metric is set to yes. Theinformation in sixth row 926 is, e.g., included in router 3 106 androuter 4 108. Each of router 3 106 and router 4 108 advertise NLM=1 forlink bundle B6 138.

Seventh row 928 indicates that link bundle B7 has a NLM=1, a limitedoperation threshold=3, a LOMLM=9, is in normal mode, currently has 9operational links, and the advertising link metric is set to yes. Theinformation in seventh row 928 is, e.g., included in router 5 110 androuter 6 112. Each of router 5 110 and router 6 112 advertise NLM=1 forlink bundle B7 140.

FIG. 10 is a drawing of a table 1000 illustrating exemplary link bundleinformation corresponding to the example of FIG. 3 and FIG. 6 . Firstcolumn 1002 includes link bundle number information used to identifyeach of the links bundles. Second column 1004 includes a normal linkmetric (NLM) value for each of the link bundles. Third column 1006includes a limited operation threshold value for each of the linkbundles. Fourth column 1008 includes a limited operation mode linkmetric (LOMLM) value for each of the link bundles. Fifth column 1010lists a current mode for each of the link bundles. Sixth column 1012lists the number of operation links for each of the link bundles, andseventh column 1014 lists whether or not a link metric is advertised,e.g., whether or not one of NLM or LOMLM, is advertised, for the linkbundle.

First row 1016 indicates that link bundle B1 has a NLM=2, a limitedoperation threshold=3, a LOMLM=9, is in limited mode, currently has 3operational links, and the advertising link metric is set to yes. Theinformation in first row 1016 is, e.g., included in router 1 102 androuter 3 106. Each of router 1 102 and router 3 106 advertise LOMLM=9for link bundle B1 128.

Second row 1018 indicates that link bundle B2 has a NLM=2, a limitedoperation threshold=3, a LOMLM=9, is in down mode, currently has 0operational links, and the advertising link metric is set to no. Theinformation in second row 1018 is, e.g., included in router 2 104 androuter 4 108. Each of router 2 104 and router 4 108 refrains fromadvertising a link metric for link bundle B2 130.

Third row 1020 indicates that link bundle B3 has a NLM=1, a limitedoperation threshold=3, a LOMLM=9, is in down mode, currently has 0operational links, and the advertising link metric is set to no. Theinformation in third row 1020 is, e.g., included in router 1 102 androuter 2 104. Each of router 1 102 and router 2 104 refrain fromadvertising a link metric for link bundle B3 132.

Fourth row 1022 indicates that link bundle B4 has a NLM=2, a limitedoperation threshold=3, a LOMLM=9, is in normal mode, currently has 9operational links, and the advertising link metric is set to yes. Theinformation in fourth row 1022 is, e.g., included in router 1 102 androuter 5 110. Each of router 1 102 and router 5 110 advertise NLM=2 forlink bundle B4 134.

Fifth row 1024 indicates that link bundle B5 has a NLM=2, a limitedoperation threshold=3, a LOMLM=9, is in down mode, currently has 0operational links, and the advertising link metric is set to no. Theinformation in fifth row 1024 is, e.g., included in router 2 104 androuter 6 112. Each of router 2 104 and router 6 112 refrain fromadvertising a link metric for link bundle B5 136.

Sixth row 1026 indicates that link bundle B6 has a NLM=1, a limitedoperation threshold=3, a LOMLM=9, is in normal mode, currently has 9operational links, and the advertising link metric is set to yes. Theinformation in sixth row 1026 is, e.g., included in router 3 106 androuter 4 108. Each of router 3 106 and router 4 108 advertise NLM=1 forlink bundle B6 138.

Seventh row 1028 indicates that link bundle B7 has a NLM=1, a limitedoperation threshold=3, a LOMLM=9, is in normal mode, currently has 9operational links, and the advertising link metric is set to yes. Theinformation in seventh row 1028 is, e.g., included in router 5 110 androuter 6 112. Each of router 5 110 and router 6 112 advertise NLM=1 forlink bundle B7 140.

FIG. 11 , comprising the combination of FIG. 11A, FIG. 11B and FIG. 11C,is a flowchart of an exemplary method of operating a first network node,e.g., a first router, in a communications network, in accordance with anexemplary embodiment. In some embodiments, the first node is, e.g., oneof router 1 102, router 2 104, router 3 106, router 4 108, router 5 110or router 6 112 of the communications network shown in FIGS. 1-6 .

Operation starts in step 1102 in which the first network node is poweredon and initialized. Operation proceeds from start step 1102 to step1104. In step 1104 the first network node determines a normal linkbundle metric for a first link bundle including a plurality ofcommunications links between the first network node a second networknode. In some embodiments, step 1104 includes steps 1106 and 1108. Insome embodiments, step 1104 includes step 1110.

In step 1106 the first network node receives input indicating a firstnormal link bundle metric corresponding to the first link bundle.Operation proceeds from step 1106 to step 1108, in which the firstnetwork nodes uses the received first normal link bundle metric as thedetermined normal link bundle metric for the first link bundle.

In step 1110 the first network node automatically generates the normallink bundle metric for the first link bundle metric using an automatedlink weight generation algorithm. In some such embodiments, step 1110includes step 1112 in which the first network node uses a link weightgeneration algorithm to generate the normal link bundle metric for thefirst link bundle.

In some embodiments, operation proceeds from step 1104 to step 1114; inother embodiments, e.g., an embodiment including step 1124, operationproceeds from step 1104 to step 1122.

In step 1114, the first network node determines a limited operation modelink bundle metric for the first link bundle. In some embodiments, step1114 includes steps 1116 and 1118. In some other embodiments, step 1114includes step 1117 and 1119. In some other embodiments, step 1114includes step 1120.

In step 1116 the first network node receives input indicating a firstlimited operation mode link bundle metric corresponding to the firstlink bundle. Operation proceeds from step 1116 to step 1118. In step1118 the first network node uses the received first limited operationmode link bundle metric as the determined limited operation mode linkbundle metric for the first link bundle.

In step 1117 the first network node receives input indicating a costfactor greater than one. Operation proceeds from step 1117 to step 1119.In step 1119 the network node multiples the first normal link metriccorresponding to the first link bundle by a cost factor greater thanone, e.g., the received cost factor from step 1117, to generate thelimited operation mode link metric for the first link bundle.

In step 1120 the first network node sets the limited operation mode linkbundle metric for the first link bundle to a maximum link metric value.For example, the limited operation mode link bundle metric is set to thelargest permitted link weight value to discourage its use where largevalues indicate links with longer paths or which are more costly in thisway causing the routing system to avoid use of the faulty link bundleunless there are no other alternative links available since the path isindicated to be the most costly a path can be. In one exemplaryembodiment, a link metric value is an integer in the range of 1 to 9,and the limited operation mode link bundle metric for the first linkbundle is set to 9.

Operation proceeds from step 1114 to step 1122. In step 1122 the firstnetwork node determines the number of good links in a first link bundleincluding a plurality of communications links between the first networknode and the second network node. In some embodiments, e.g., anembodiment in which step 1114 is omitted, operation proceeds from step1122 to step 1124. In some other embodiments, e.g., an embodiment inwhich step 1114 is includes, operation proceeds from step 1122, viaconnecting node A 1128, to step 1130.

In step 1124, the first network node determines a limited operation modelink bundle metric for the first link bundle. In some embodiments, step1124 includes one or both of step 1125 and step 1126. In step 1125 thefirst network node determines a cost factor greater than one as afunction of the determined number of good links in the first linkbundle. Operation proceeds from step 1125 to step 1126. In step 1126 thefirst network node multiples the first normal link metric correspondingto the first link bundle by a cost factor greater than one, e.g., thecost factor determined in step 1125, to generate the limited operationmode link bundle metric for the first link bundle. In some embodiments,the cost factor is a function of the current number of good links. Insome embodiments, the cost factor is larger when the number of goodlinks in the first bundle is less than a first limited operation modenumber of links than when the number of good links is equal to the firstlimited operation number of links. For example, a larger cost factor isgenerated in step 1125 when the number of good links in the first bundleis one, than when the number of good links in the first bundle equalsthe first limited operation number of good links, e.g. equals 3.Operation proceeds from step 1124, via connecting node A 1128, to step1130.

In step 1130 the first network node makes a first link bundle metricadvertising decision, said first link bundle metric advertising decisionbeing a decision to: i) advertise the normal link bundle metric for thefirst link bundle; ii) advertise the limited operation mode link bundlemetric for the first link bundle; or iii) perform no advertising of alink bundle metric for the first link bundle. Step 1130 includes steps1132, 1134, 1136, 1138, 1140, 1142, 1144 and 1146.

In step 1132 the first network node determines if the current number ofgood links in the first link bundle is above a first limited operationmode number of links, e.g. a limited operation threshold number. In someembodiments, when determined number of good links is above the firstlimited operation mode number of links this indicates that the firstlink bundle is operating in normal mode with all good links or with atleast a sufficient number of good links to support normal link bundlemode operation, e.g., with a sufficient number of links to support anormal expected load traffic. Operation proceeds from step 1132 to step1134.

In step 1134, if the determination is that the current number of goodlinks in the first link bundle is above the first limited operation modenumber of links, then operation proceeds from step 1134 to step 1136;otherwise, operation proceeds from step 1134 to step 1138. In step 1138the first network node decides to advertise the normal link bundlemetric for the first link bundle.

In step 1138 the first network node determines if the current number ofgood links in the first link bundle is a non-zero number of good linkswhich is equal to or below the first limited operation number of links.Operation proceeds from step 1138 to step 1140.

In step 1140 if the determination is that the current number of goodlinks in the first link bundle is a non-zero number of good links whichis equal to or below the first limited operation number of links, thenoperation proceeds from step 1140 to step 1142; otherwise, operationproceeds from step 1140 to step 1144.

In step 1142 the first network node decides to advertise the limitedoperation mode link bundle metric for the first link bundle. Returningto step 1144, in step 1144 the first network node determines that thecurrent number of good links in the first link bundle is zero. Operationproceeds from step 1144 to step 1146. In step 1146, the first networknode decides not to advertise a link bundle metric for the first linkbundle. Step 1146 includes step 1148 in which the first network nodedecides not to advertise the limited operation mode link bundle metricfor the first link bundle. For example, when the number of good links inthe first link bundle is zero, no link metric will be advertised for thefirst link bundle and thus devices will not consider using the firstlink bundle as a viable link when making routing decisions based onadverted link metrics, e.g., link weights which can be used for shortestpath first, lowest cost path routing or other forms of link weight basedrouting decisions.

Operation proceeds from step 1130, via connecting node B 1150, to step1152. In step 1152 the first network node takes and advertising actionin accordance with the determined first link bundle metric advertisingdecision, said advertising action including operating the first networknode to: i) advertise the normal link bundle metric for the first linkbundle; ii) advertise the limited operation mode link bundle metric forthe first link bundle; or iii) control the first network node to refrainfrom advertising a link bundle metric for the first link bundle. Step1152 includes steps 1154, 1156, 1158, 1162 and 1166.

In step 1154 the first network node determines if first link metricadvertising decision is a decision to advertise one of the normal linkmetric or the limited operation mode link metric for the first linkbundle. If the determination is that the first link metric advertisingdecision is a decision to advertise one of the normal link metric or thelimited operation mode link metric for the first link bundle, thenoperation proceeds from step 1154 to step 1156; otherwise, operationproceeds from step 1154 to step 1166. In step 1156 the first networknode determines if the determined first link metric advertising decisionis a decision to advertise a normal link metric. If the decision is adecision to advertise the normal link metric, then operation proceedsfrom step 1156 to step 1158; otherwise operation proceeds from step 1156to step 1162.

In step 1158 the first network node is operated to advertise the normallink metric for the first link bundle. Step 1158 includes step 1160 inwhich the first network node operates a transmitter in the first networknode to transmit the normal link bundle metric for the first linkbundle. In some embodiments the transmitted normal link bundle metric iscommunicated in a routing protocol signal, e.g., an Open Shortest PathFirst (OSPF) routing protocol signal, an Intermediate System toIntermediate System (IS-IS) routing protocol signal, or a Border GatewayProtocol (BGP) routing protocol signal, which is used to facilitaterouting decisions.

Returning to step 1162, in step 1162 the first network node is operatedto advertise the limited operation mode link bundle metric for the firstlink bundle. Step 1162 includes step 1164 in which the first networknode operates a transmitter in the first network node to transmit thelimited operation mode link bundle metric for the first link bundle. Insome embodiments the transmitted limited operation link bundle metric iscommunicated in a routing protocol signal, e.g., an Open Shortest PathFirst (OSPF) routing protocol signal, an Intermediate System toIntermediate System (IS-IS) routing protocol signal, or a Border GatewayProtocol (BGP) routing protocol signal, which is used to facilitaterouting decisions.

Returning to step 1166, in step 1166 the first network node is operatedto control the first network node to refrain from advertising a linkbundle metric for the first link bundle. Step 1166 includes step 1168 inwhich the first network node sets a value in memory indicating that alink bundle metric is not to be transmitted for the first link bundle.

Operation proceeds from step 1152, via connecting node C 1170 to step1122.

The flowchart 1100 of FIG. 11 has been described for an example of thefirst network node monitoring status, determining link metrics andperforming a link metric advertising decision, and implementing the linkmetric advertising decision for a first link bundle. It should beappreciated that the first network node may, and sometimes does, performsimilar operations for other link bundles, e.g. a second link bundleincluding a plurality of connections between the first network node anda third network node.

FIG. 12 is a drawing of an exemplary node 1200, e.g., network node,e.g., a router, in accordance with an exemplary embodiment. Exemplarynode 1200 is, e.g., one of the routers (102, 104, 106, 108, 110, 112) ofFIGS. 1-6 , a node implementing the method of flowchart 700 of FIG. 7and/or a node implementing the method of flowchart 1100 of FIG. 11 .

Exemplary node 1200 includes a processor 1202, e.g., a CPU, a routingcontroller 1203, a network interface 1204, an input device 1206, e.g.,keyboard, an output device 1208, e.g., display, an assembly of hardwarecomponents 1210, e.g., an assembly of circuits, and memory 1212 coupledtogether via a bus 1214 over which the various elements may interchangedata and information. The network interface 1204, e.g., a wired oroptical interface, includes a plurality of line cars (line card 1 (LC1)1250, LC 2 1252, . . . , LC X 1254). Each line card includes a pluralityof receiver/transmitter pairs sometimes referred to as ports. LC 1 1250includes receiver 1 (RX 1) 1246, transmitter 1 (TX 1) 1258; RX 2 1260,TX2 1262; . . . ; RX M 1264, TX M 1266. Each receiver/transmitter pairis coupled to a physical connection, e.g., physical link.

In the simplified example, of FIGS. 4-6 , 9 physical links are shown ascorresponding to an exemplary link bundle. In general, a bundle may ormay not encompass each of the RX/TX pairs on a line card. A bundle may,and frequently does, share ports on a line card with other bundles. Invarious embodiments, a link bundle is represented by a link metric, e.g.a link bundle metric such as a normal link metric (NLM) or a limitedoperation mode link metric (LOMLM), which may be, and sometimes is,advertised, e.g. for routing purposes.

Memory 1212 includes a control routine 1220, an assembly of components122, e.g., an assembly of software components, and data/information1224. Data/information 1224 includes link bundle information includinglink bundle 1 information 1270, . . . , link bundle N information 1272.Data/information 1274 further includes generated link metricadvertisements signals 1274.

FIG. 13 , comprising the combination of FIG. 13A, FIG. 13B and FIG. 13C,is a drawing of an exemplary assembly of components 1300 in accordancewith an exemplary embodiment. Assembly of components 1300 is, e.g.,included in a node, e.g., a router 102, 104, 106, 108, 110 or 112 ofFIG. 1-6 , and/or node 1200, e.g., a network node such as a router ofFIG. 12 and implement steps of an exemplary method, e.g., steps of themethod of the flowchart 700 of FIG. 7 and/or steps of flowchart 1100 ofFIG. 11 .

Assembly of components 1300 can be, and in some embodiments is, used innode 1200 of FIG. 12 . The components in the assembly of components 1300can, and in some embodiments are, implemented fully in hardware withinthe processor 1202, e.g., as individual circuits. The components in theassembly of components 1300 can, and in some embodiments are,implemented fully in hardware within the assembly of components 1210,e.g., as individual circuits corresponding to the different components.In other embodiments some of the components are implemented, e.g., ascircuits, within the processor 1202 with other components beingimplemented, e.g., as circuits within assembly of components 1210,external to and coupled to the processor 1202. As should be appreciatedthe level of integration of components on the processor and/or with somecomponents being external to the processor may be one of design choice.Alternatively, rather than being implemented as circuits, all or some ofthe components may be implemented in software and stored in the memory1212 of the node 1200, with the components controlling operation of thenode 1200 to implement the functions corresponding to the componentswhen the components are executed by a processor, e.g., processor 1202.In some such embodiments, the assembly of components 1300 is included inthe memory 1212 as assembly of components 1222. In still otherembodiments, various components in assembly of components 1300 areimplemented as a combination of hardware and software, e.g., withanother circuit external to the processor providing input to theprocessor 1202 which then under software control operates to perform aportion of a component's function. While processor 1202 is shown in theFIG. 12 embodiment as a single processor, e.g., computer, it should beappreciated that the processor 1202 may be implemented as one or moreprocessors, e.g., computers. In some embodiments, one or more of thecomponents in assembly of components 1300 are included in routingcontroller 1203.

When implemented in software the components include code, which whenexecuted by the processor 1202, configure the processor 1202 toimplement the function corresponding to the component. In embodimentswhere the assembly of components 1300 is stored in the memory 1212, thememory 1212 is a computer program product comprising a computer readablemedium comprising code, e.g., individual code for each component, forcausing at least one computer, e.g., processor 1202, to implement thefunctions to which the components correspond

Completely hardware based or completely software based components may beused. However, it should be appreciated that any combination of softwareand hardware, e.g., circuit implemented components may be used toimplement the functions. As should be appreciated, the componentsillustrated in FIG. 13 control and/or configure the node 1200, orelements therein such as the processor 1202, to perform the functions ofcorresponding steps illustrated and/or described in the method of one ormore of the flowcharts, signaling diagrams and/or described with respectto any of the Figures. Thus the assembly of components 1300 includesvarious components that perform functions of corresponding one or moredescribed and/or illustrated steps of an exemplary method, e.g., stepsof the method of flowchart 700 of FIG. 7 , the flowchart 1100 of FIG. 11and/or described or shown with respect to any of the other figures.

Assembly of components 1300 includes a component 1304 configured todetermine a normal link bundle metric for a first link bundle includinga plurality of communications links between the first network node and asecond network node, a component 1314 configured to determine a limitedoperation mode link bundle metric for the first link bundle, a componentconfigured to determine a number of good links in the first link bundleincluding a plurality of communications links between the first networknode and the second network node. Component 1304 includes a component1306 configured to receive input indicating a first normal link bundlemetric corresponding to the first link bundle, a component 1308configured to use the received first normal link bundle metric as thedetermined normal link bundle metric for the first link bundle.Component 1304 further includes a component 1310 configured toautomatically generate the normal link bundle metric for the first linkbundle using an automated link weight generation algorithm. Component1304 includes a component 1312 configured to use a shortest path firstweight generation algorithm to generate the normal link bundle metricfor the first link bundle. Component 1314 includes a component 1316configured to receive input indicating a first limited operation modelink bundle metric corresponding to the first link bundle, a component1318 configured to use the received first limited operation link bundlemetric as the determined limited operation link bundle metric for thefirst link bundle, a component 1317 configured to receive user inputindicating a cost factor greater than one, a component 1317 configuredto multiply the first normal link metric corresponding to the first linkbundle by a cost factor greater than one to generate the limitedoperation mode link bundle metric for the first link bundle, and acomponent 1320 configured to set the limited operation mode link bundlemetric for the first link bundle to a maximum link metric value.

In some embodiments, assembly of components 1300 includes component 1324configured to determine a limited operation mode link bundle metric,e.g., in place of component 1314. In some embodiments, component 1324includes one or both of a component 1325 configured to determine a costfactor greater than one as a function of the determined number of goodlinks in the first link bundle and a component 1326 configured tomultiply the first normal link metric corresponding to the first linkbundle by a cost factor greater than one to generate the limitedoperation mode link bundle metric for the first link bundle.

Assembly of components 1300 further includes a component 1330 configuredto make a first link bundle metric advertising decision, said first linkbundle metric advertising decision being a decision to: i) advertise thenormal link bundle metric for the first link bundle; ii) advertise thelimited operation link bundle metric of the first link bundle; or iii)perform no advertising of a link bundle metric for the first linkbundle. Component 1330 includes a component 1332 configured to determineif a current number of good link in the first link bundle is above afirst limited operation number of links, a component 1334 configured tocontrol operation as a function of the determination if the currentnumber of good links in the first link bundle is above the first limitedoperation mode number of links, and a component 1336 configured todecide to advertise the normal link bundle metric for the first linkbundle in response to a determination that the current number of goodlinks in the first link bundle is above the first limited operation modenumber of links. Assembly of components 1330 further includes acomponent 1138 configured to determine if the current number of goodlinks in the first link bundle is a non-zero number of good links whichis equal to or below the first limited operation number of links, acomponent 1340 configured to control operation as a function of thedetermination if the current number of good links in the first linkbundle is a non-zero number of good links which is equal to or below thefirst limited operation mode number of links, a component 1342configured to decide to advertise the limited operation mode link bundlemetric for the first link bundle in response to a determination that thecurrent number of good links in the first link bundle is a non-zeronumber of good links which is equal to or below the first limitedoperation number of links. Component 1330 further includes a component1342 configured to determine that the current number of good links inthe first link bundle is zero, and a component 1346 configured to decidenot to advertise a link bundle metric for the first link bundle inresponse to determining that there are not currently any good links inthe first link bundle. Component 1346 includes a component configured todecide not to advertise the limited operation mode link bundle metricfor the first link bundle and a component 1349 configured to decide notto advertise the normal link bundle metric for the first link bundle.

Assembly of components 1300 further includes a component 1352 configuredto take an advertising action in accordance with the determined firstlink bundle metric advertising decision, said advertising actionincluding operating the first node to: i) advertise the normal linkbundle metric for the first link bundle; ii) advertise the limitedoperation link bundle metric for the first link bundle; or iii) controlthe first node to refrain from advertising a link bundle metric for thefirst link bundle. Component 1352 includes a component 1354 configuredto determine if the first link metric advertising decision is a decisionto advertise one of the normal link metric or the limited operation modemetric for the first link bundle and to control operation as a functionof the determination, a component 1356 configured to determine if thefirst link metric advertising decision is a decision to advertise thenormal link metric and to control operation as a function of thedetermination. Component 1352 further includes a component 1358configured to operate the first node to advertise the normal link bundlemetric for the first link bundle in response to a determination that theadvertising decision is a decision to advertise the normal link bundlemetric for the first link bundle, a component 1362 configured to operatethe first node to advertise the limited operation mode link bundlemetric for the first link bundle in response to a determination that theadvertising decision is a decision to advertise the limited operationmode link bundle metric for the first link bundle, and a component 1366configured to operate the first node to control the first node torefrain from advertising a link bundle metric for the first link bundle,in response to a determination that the advertising decision is adecision not to advertises either one of the normal link metric or thelimited operation link metric for the first link bundle.

Component 1358 includes a component 1360 configured to operate atransmitter in the first node to transmit the normal link bundle metricfor the first link bundle. Component 1362 includes a component 1364configured to operate a transmitter in the first node to transmit thelimited operation mode link bundle metric for the first link bundle.Component 1366 includes a component 1368 configured to set a value inmemory indicating that a link bundle metric is not to be transmitted forthe first link bundle.

FIG. 14 is a drawing 1400, corresponding to the example of FIG. 1 andFIG. 4 , which illustrates examples of exemplary selected communicationspaths 1402, 1404 which were selected using the advertised link metricsin accordance with an exemplary embodiment. Exemplary communicationspath 1402 between CPE/user device 1 114 and CPE/user device 3 118traverses link 142, router 3 106, link bundle B1 128, router 1 102, linkbundle B4 134, router 5 110 and link 146. Exemplary communications path1404 between CPE/user device 2 116 and CPE/user device 4 120 traverseslink 144, router 4 108, link bundle B2 130, router 2 104, link bundle B5136, router 6 112 and link 148.

FIG. 15 is a drawing 1500, corresponding to the example of FIG. 2 andFIG. 5 , which illustrates examples of exemplary selected communicationspaths 1502, 1504 which were selected using the advertised link metricsin accordance with an exemplary embodiment. Exemplary communicationspath 1502 between CPE/user device 1 114 and CPE/user device 3 118traverses link 142, router 3 106, link bundle B6 138, router 4 108, linkbundle B2 130, router 2 104, link bundle B3 132, router 1 102, linkbundle B4 134, router 5 110 and link 146. Exemplary communications path1504 between CPE/user device 2 116 and CPE/user device 4 120 traverseslink 144, router 4 108, link bundle B2 130, router 2 104, link bundle B5136, router 6 112 and link 148.

FIG. 16 is a drawing 1600, corresponding to the example of FIG. 3 andFIG. 6 , which illustrates examples of exemplary selected communicationspaths 1602, 1604 which were selected using the advertised link metricsin accordance with an exemplary embodiment. Exemplary communicationspath 1602 between CPE/user device 1 114 and CPE/user device 3 118traverses link 142, router 3 106, link bundle B1 128, router 1 102, linkbundle B4 134, router 5 110 and link 146. Exemplary communications path1604 between CPE/user device 2 116 and CPE/user device 4 120 traverseslink 144, router 4 108, link bundle B6 138, router 3 106, link bundle B1128, router 1 102, link bundle B4 134, router 5 110, link bundle B7 140,router 6 112, and link 148.

FIG. 17 is a drawing of a table 1700 illustrating exemplary bundleinformation for an exemplary link bundle, wherein the limited operationmode link metric for the link bundle is a maximum link weight value, inaccordance with an exemplary embodiment. First column 1702 includes timeinformation. Second column 1704 includes normal link metric (NLM) valuesfor the link bundle at different times. Third column 1706 includes alimited operation threshold value for the link bundle at differenttimes. Fourth column 1708 includes a limited operation mode link metric(LOMLM) value for the link bundle at different times. Fifth column 1710lists a current mode for the link bundle at different times. Sixthcolumn 1712 lists the number of operational links for the link bundle atdifferent times, and seventh column 1714 lists whether or not a linkmetric is advertised, e.g., whether or not one of NLM or LOMLM, isadvertised at different times, for the link bundle.

First row 1716 indicates that at time T0, the link bundle has a NLM=2, alimited operation threshold=3, a LOMLM=9, currently has 9 operationallinks, is in normal mode and the advertising link metric indicator isset to yes. Thus, the normal link metric, which has a value of 2, willbe advertised.

Second row 1718 indicates that at time T1, the link bundle has a NLM=2,a limited operation threshold=3, a LOMLM=9, currently has 7 operationallinks, is in normal mode, and the advertising link metric indicator isset to yes. Thus, the normal link metric, which has a value of 2, willbe advertised.

Third row 1720 indicates that at time T2, the link bundle has a NLM=2, alimited operation threshold=3, a LOMLM=9, currently has 4 operationallinks, is in normal mode, and the advertising link metric indicator isset to yes. Thus, the normal link metric, which has a value of 2, willbe advertised.

Fourth row 1722 indicates that at time T3, the link bundle has a NLM=2,a limited operation threshold=3, a LOMLM=9, currently has 3 operationallinks, is in limited operation mode, and the advertising link metricindicator is set to yes. Thus, the limited operation mode link metric,which has a value of 9, will be advertised.

Fifth row 1724 indicates that at time T4, the link bundle has a NLM=2, alimited operation threshold=3, a LOMLM=9, currently has 1 operationallink, is in limited operation mode, and the advertising link metricindicator is set to yes. Thus, the limited operation mode link metric,which has a value of 9, will be advertised.

Sixth row 1726 indicates that at time T4, the link bundle has a NLM=2, alimited operation threshold=3, a LOMLM=9, currently has 0 operationallinks, is in down mode, and the advertising link metric indicator is setto no. Thus, neither the normal link metric nor the limited operationmode link metric will be advertised, and the node is controlled torefrain from transmitting a link metric corresponding to the linkbundle.

FIG. 18 is a drawing of a table 1800 illustrating exemplary bundleinformation for an exemplary first link bundle, wherein the limitedoperation mode link metric for the first link bundle is a multiple,e.g., 4X, of the normal link metric for the first link bundle, inaccordance with an exemplary embodiment. First column 1802 includes timeinformation. Second column 1804 includes normal link metric (NLM) valuesfor the link bundle at different times. Third column 1806 includes alimited operation threshold value for the link bundle at differenttimes. Fourth column 1808 includes a limited operation mode link metric(LOMLM) value for the link bundle at different times. Fifth column 1810lists a current mode for the link bundle at different times. Sixthcolumn 1812 lists the number of operational links for the link bundle atdifferent times, and seventh column 1814 lists whether or not a linkmetric is advertised, e.g., whether or not one of NLM or LOMLM, isadvertised at different times, for the link bundle.

First row 1816 indicates that at time T0, the first link bundle has aNLM=2, a limited operation threshold=3, a LOMLM=8, currently has 9operational links, is in normal mode and the advertising link metricindicator is set to yes. Thus, the normal link metric, which has a valueof 2, will be advertised.

Second row 1818 indicates that at time T1, the first link bundle has aNLM=2, a limited operation threshold=3, a LOMLM=8, currently has 7operational links, is in normal mode, and the advertising link metricindicator is set to yes. Thus, the normal link metric, which has a valueof 2, will be advertised.

Third row 1820 indicates that at time T2, the first link bundle has aNLM=2, a limited operation threshold=3, a LOMLM=8, currently has 4operational links, is in normal mode, and the advertising link metricindicator is set to yes. Thus, the normal link metric, which has a valueof 2, will be advertised.

Fourth row 1822 indicates that at time T3, the first link bundle has aNLM=2, a limited operation threshold=3, a LOMLM=8, currently has 3operational links, is in limited operation mode, and the advertisinglink metric indicator is set to yes. Thus, the limited operation modelink metric, which has a value of 8, will be advertised.

Fifth row 1824 indicates that at time T4, the first link bundle has aNLM=2, a limited operation threshold=3, a LOMLM=8, currently has 1operational link, is in limited operation mode, and the advertising linkmetric indicator is set to yes. Thus, the limited operation mode linkmetric, which has a value of 8, will be advertised.

Sixth row 1826 indicates that at time T4, the first link bundle has aNLM=2, a limited operation threshold=3, a LOMLM=8, currently has 0operational links, is in down mode, and the advertising link metricindicator is set to no. Thus, neither the normal link metric nor thelimited operation mode link metric will be advertised, and the node iscontrolled to refrain from transmitting a link metric corresponding tothe link bundle.

FIG. 19 is a drawing of a table 1900 illustrating exemplary bundleinformation for an exemplary second link bundle, wherein the limitedoperation mode link metric for the second link bundle is multiple, e.g.,4X, of the normal link metric for the second link bundle, in accordancewith an exemplary embodiment. First column 1902 includes timeinformation. Second column 1904 includes normal link metric (NLM) valuesfor the link bundle at different times. Third column 1906 includes alimited operation threshold value for the link bundle at differenttimes. Fourth column 1908 includes a limited operation mode link metric(LOMLM) value for the link bundle at different times. Fifth column 1910lists a current mode for the link bundle at different times. Sixthcolumn 1912 lists the number of operational links for the link bundle atdifferent times, and seventh column 1914 lists whether or not a linkmetric is advertised, e.g., whether or not one of NLM or LOMLM, isadvertised at different times, for the link bundle.

First row 1916 indicates that at time T0, the second link bundle has aNLM=1, a limited operation threshold=3, a LOMLM=4, currently has 9operational links, is in normal mode and the advertising link metricindicator is set to yes. Thus, the normal link metric, which has a valueof 2, will be advertised.

Second row 1918 indicates that at time T1, the second link bundle has aNLM=1, a limited operation threshold=3, a LOMLM=4, currently has 7operational links, is in normal mode, and the advertising link metricindicator is set to yes. Thus, the normal link metric, which has a valueof 2, will be advertised.

Third row 1920 indicates that at time T2, the second link bundle has aNLM=1, a limited operation threshold=3, a LOMLM=4, currently has 4operational links, is in normal mode, and the advertising link metricindicator is set to yes. Thus, the normal link metric, which has a valueof 2, will be advertised.

Fourth row 1922 indicates that at time T3, the second link bundle has aNLM=1, a limited operation threshold=3, a LOMLM=4, currently has 3operational links, is in limited operation mode, and the advertisinglink metric indicator is set to yes. Thus, the limited operation modelink metric, which has a value of 4, will be advertised.

Fifth row 1924 indicates that at time T4, the second link bundle has aNLM=1, a limited operation threshold=3, a LOMLM=4, currently has 1operational link, is in limited operation mode, and the advertising linkmetric indicator is set to yes. Thus, the limited operation mode linkmetric, which has a value of 4, will be advertised.

Sixth row 1926 indicates that at time T4, the second link bundle has aNLM=1, a limited operation threshold=3, a LOMLM=4, currently has 0operational links, is in down mode, and the advertising link metricindicator is set to no. Thus, neither the normal link metric nor thelimited operation mode link metric will be advertised, and the node iscontrolled to refrain from transmitting a link metric corresponding tothe link bundle.

FIG. 20 is a drawing of a table 2000 illustrating exemplary bundleinformation for an exemplary link bundle, wherein the limited operationmode link metric for the link bundle is a function of the determinednumber of operational links in the link bundle, in accordance with anexemplary embodiment. First column 2002 includes time information.Second column 2004 includes normal link metric (NLM) values for the linkbundle at different times. Third column 2006 includes a limitedoperation threshold value for the link bundle at different times. Fourthcolumn 2008 lists the number of operation links for the link bundle atdifferent times. Fifth column 2009 lists a cost factor value for thelink bundle at different times. Sixth column 2010 includes a limitedoperation mode link metric (LOMLM) value for the link bundle atdifferent times. Seventh column 2012 lists a current mode for the linkbundle at different times, and eighth column 2014 lists whether or not alink metric is advertised, e.g., whether or not one of NLM or LOMLM, isadvertised at different times, for the link bundle.

First row 2016 indicates that at time T0, the link bundle has a NLM=2, alimited operation threshold=3, currently has 9 operational links, has acost factor of 3.5, has a LOMLM=7, is in normal mode and the advertisinglink metric indicator is set to yes. Thus, the normal link metric, whichhas a value of 2, will be advertised.

Second row 2018 indicates that at time T1, the link bundle has a NLM=2,a limited operation threshold=3, currently has 4 operational links, hasa cost factor of 3.5, has a LOMLM=7, is in normal mode and theadvertising link metric indicator is set to yes. Thus, the normal linkmetric, which has a value of 2, will be advertised.

Third row 2020 indicates that at time T2, the link bundle has a NLM=2, alimited operation threshold=3, currently has 3 operational links, has acost factor of 3.5, has a LOMLM=7, is in limited operation mode and theadvertising link metric indicator is set to yes. Thus, the limitedoperation mode link metric, which has a value of 7, will be advertised.

Fourth row 2022 indicates that at time T3, the link bundle has a NLM=2,a limited operation threshold=3, currently has 2 operational links, hasa cost factor of 4, has a LOMLM=8, is in limited operation mode and theadvertising link metric indicator is set to yes. Thus, the limitedoperation mode link metric, which has a value of 8, will be advertised.

Fifth row 2024 indicates that at time T4, the link bundle has a NLM=2, alimited operation threshold=3, currently has 1 operational links, has acost factor of 4.5, has a LOMLM=9, is in limited operation mode and theadvertising link metric indicator is set to yes. Thus, the limitedoperation mode link metric, which has a value of 9, will be advertised.Sixth row 2026 indicates that at time T5, the link bundle has a NLM=2, alimited operation threshold=3, currently has 0 operational links, has acost factor of 4.5, has a LOMLM=9, is in down mode and the advertisinglink metric indicator is set to no. Thus, neither the normal link metricnor the limited operation mode link metric for the link bundle will beadvertised.

FIG. 21 , comprising the combination of FIG. 21A, FIG. 21B and FIG. 21C,is a drawing of an exemplary assembly of components 2100, comprising thecombination of Part A 2101, Part B 2103 and Part C 2105, which may beincluded in an exemplary communications device, e.g., a router, inaccordance with an exemplary embodiment. Assembly of components 2100 is,e.g., included in a node, e.g., a router 102, 104, 106, 108, 110 or 112of FIG. 1-6 , and/or node 1200, e.g., a network node such as a router ofFIG. 12 and implement steps of an exemplary method, e.g., steps of themethod of the flowchart 700 of FIG. 7 and/or steps of flowchart 1100 ofFIG. 11 .

Assembly of components 2100 can be, and in some embodiments is, used innode 1200 of FIG. 12 . The components in the assembly of components 2100can, and in some embodiments are, implemented fully in hardware withinthe processor 1202, e.g., as individual circuits. The components in theassembly of components 2100 can, and in some embodiments are,implemented fully in hardware within the assembly of components 1210,e.g., as individual circuits corresponding to the different components.In other embodiments some of the components are implemented, e.g., ascircuits, within the processor 1202 with other components beingimplemented, e.g., as circuits within assembly of components 1210,external to and coupled to the processor 1202. As should be appreciatedthe level of integration of components on the processor and/or with somecomponents being external to the processor may be one of design choice.Alternatively, rather than being implemented as circuits, all or some ofthe components may be implemented in software and stored in the memory1212 of the node 1200, with the components controlling operation of thenode 1200 to implement the functions corresponding to the componentswhen the components are executed by a processor, e.g., processor 1202.In some such embodiments, the assembly of components 2100 is included inthe memory 1212 as assembly of components 1222. In still otherembodiments, various components in assembly of components 2100 areimplemented as a combination of hardware and software, e.g., withanother circuit external to the processor providing input to theprocessor 1202 which then under software control operates to perform aportion of a component's function. While processor 1202 is shown in theFIG. 12 embodiment as a single processor, e.g., computer, it should beappreciated that the processor 1202 may be implemented as one or moreprocessors, e.g., computers. In some embodiments, one or more of thecomponents in assembly of components 2100 are included in routingcontroller 1203.

When implemented in software the components include code, which whenexecuted by the processor 1202, configure the processor 1202 toimplement the function corresponding to the component. In embodimentswhere the assembly of components 2100 is stored in the memory 1212, thememory 1212 is a computer program product comprising a computer readablemedium comprising code, e.g., individual code for each component, forcausing at least one computer, e.g., processor 1202, to implement thefunctions to which the components correspond

Completely hardware based or completely software based components may beused. However, it should be appreciated that any combination of softwareand hardware, e.g., circuit implemented components may be used toimplement the functions. As should be appreciated, the componentsillustrated in FIG. 21 control and/or configure the node 1200, orelements therein such as the processor 1202, to perform the functions ofcorresponding steps illustrated and/or described in the method of one ormore of the flowcharts, signaling diagrams and/or described with respectto any of the Figures. Thus the assembly of components 2100 includesvarious components that perform functions of corresponding one or moredescribed and/or illustrated steps of an exemplary method, e.g., stepsof the method of flowchart 700 of FIG. 7 , the flowchart 1100 of FIG. 11and/or described or shown with respect to any of the other figures.

Assembly of components 2100 includes a component 2104 configured todetermine normal operation mode link bundle metrics, e.g., one per linksbundle. Component 2104 includes a component 2106 configured to receiveinput indicating a normal link metric for each link bundle and acomponent 2108 configured to automatically generate, on a per linkbundle basis, a normal link metric for each link bundle.

Assembly of components 2100 further includes a component 2110 configuredto store a normal operation link metric for each link bundle in memory,and a component 2112 configured to receive limited operation thresholdinformation, on a per link bundle basis, e.g., a value indicating anumber of links in a link bundle which is to trigger limited operationmode for the link bundle. In some embodiments, the value indicating anumber of links in the link bundle which is to trigger limited operationmode for the link bundle indicates a failed number of links in thebundle. In some embodiments, the value indicating a number of links inthe link bundle which is to trigger limited operation mode for the linkbundle indicates a number of operational, e.g., good links in the linkbundle, which is the maximum number of good links for limited operationmode for the link bundle. In some such embodiments, the value indicatinga number of links in the link bundle which is to trigger limitedoperation mode for the link bundle is a limited operation thresholdvalue, e.g., a limited operation mode number of links for the linkbundle.

Assembly of components 2100 further includes a component 2112 configuredto store the limited operation threshold information in memory, and acomponent configured to determine limited operation mode link bundlemetrics, e.g., one per bundle, to be advertised during limited operationmode of link bundle operation. Component 2118 includes a component 2120configured to receive input, e.g., a maximum bundle link weight, on aper link bundle basis, indicating the limited operation mode link metricfor each link bundle, and a component 2122 configured to automaticallygenerate, on a per link bundle basis, a limited operation mode linkmetric for each link bundle. Component 2122 includes a componentconfigured to multiply a normal link metric for a link by a multiplierfactor to generate a limited operation mode link metric for the linkbundle.

Assembly of components 2100 further includes a component 2126 configuredto store limited operation mode link metrics in memory, e.g., in a perlink bundle basis. Component 2126 includes a component 2128 configuredto store, e.g., in memory, a limited operation mode link metric for thefirst link bundle. In some embodiments, component 2116 includes acomponent 2130 configured to store a limited operation mode link metricfor the Nth link bundle.

Assembly of components 2100 further includes a component 2132 configuredto monitor the status of links in each link bundle, e.g., determine thenumber of operational links in each link bundle and/or determine thenumber of failed links in each link bundle. Component 2132 includes acomponent 2134 configured to determine the number of operation links inthe first link bundle, a component 2136 configured to determine thenumber of operational links in the second link bundle, and a component2138 configured to determine the number of operational links in the Nthlink bundle.

Assembly of components 2100 further includes a component configured todetermine if the determined number of links in the link bundle is aninitially determined value for the link bundle and to control operationas a function of the determination. Assembly of components 2100 furtherincludes a component 2143 configured to store the determined number ofoperational links for the link bundle in memory as the number ofcurrently operational links for the link bundle.

Assembly of components 2100 further includes a component 2142 configuredto determine if the number of operational links in the link bundle haschanged, e.g., to determine if the status of the link bundle with regardto the number of operational links has changed from the last monitoringperiod, e.g. due to one or more recently failed links in the link bundleand/or due to one or more recently repaired or improved links in thelink bundle, and to control operation as a function of thedetermination, a component 2148 configured to update the number ofcurrently operational links in memory for the link bundle to thedetermined number of operational links in the link bundle, e.g. inresponse to a determination the number of operational links in the linkbundle has changed, and a component 2144 configured to leave the numberof currently operational link in memory for the link bundle unchanged,e.g. in response to a determination that the determined number ofoperational links in the link bundle has not changed.

Assembly of components 2100 further includes a component 2150 configuredto determine if the current number of operational links, e.g. goodlinks, in the link bundle is above the limited operation thresholdnumber for the link bundle and to control operation as a function of thedetermination, a component 2154 configured to set the current mode ofoperation for the link bundle, e.g., in memory, to normal operationmode, e.g., in response to a determination that the current number ofoperational links in the link bundle is above the limited operation modethreshold number for the link bundle, and a component 2156 configured toset the advertise link metric indicator to advertise, e.g., set theindicator to yes for advertise, e.g. in response to the determinationthat the current number of operational links is above the limitedoperation threshold number for the link bundle, and a component 2158configured to advertise the normal operation link metric for the linkbundle, e.g. in response to the determination that the current mode ofoperation for the link bundle is normal operation mode and the advertiselink metric indicator is set to yes. In some embodiments, component 2158is configured to control a transmitter in the node to transmit thenormal link metric for the link bundle.

Assembly of components 2100 further includes a component 2160 configuredto determine if there are any operational links in the link bundle,e.g., determine if the number of operational links in the link bundle isgreater than zero, and to control operation as a function of thedetermination, a component 2162 configured to set the adverse linkmetric indicator to no, e.g. in response to a determination that thereare zero currently operational links in the link bundle, and a component2163 configured to control the node to refrain from advertising a linkmetric for the link bundle when the advertise link metric indicator forthe link bundle is set to a no.

Assembly of components 2100 further includes a component 2164 configuredto determine that the number of operation links in the link bundle is anumber which triggers limited operation mode of operating the linkbundle, e.g. in response to a determination that the number of currentlyoperational links in the link bundle is a value in the range of {1, . .. limited operation threshold number}, including the endpoints of therange. Assembly of components, 2100 further includes a component 2166configured to set the current mode of bundle operation to limitedoperation mode, e.g., set an indicator in memory to indicate limitedoperation mode for the link bundle, e.g., in response to thedetermination that the number of operational links is a number whichtriggers limited operation mode for the link bundle. Assembly ofcomponents 2100 further includes a component 2166 configured to set theadvertise link metric indicator for the link bundle to yes, e.g., inresponse to the currently mode of operation for the link bundle beingset to limited operation mode, and a component 2170 configured toadvertise the limited operation mode link metric for the link bundle,e.g., in response the link bundle mode of operation being limitedoperation mode and the advertise link metric indicator being set to yes.In some embodiments, component 2170 is configured to control atransmitter in the node to transmit the limited operation link metricfor the link bundle.

First Numbered List of Exemplary Embodiments

Method Embodiment 1 A method of operating a first network node in acommunications network, the method comprising: determining (1104) anormal link bundle metric for a first link bundle including a pluralityof communications links between a first network node and a secondnetwork node; determining (1114 or 1124) a limited operation mode linkbundle metric for the first link bundle; making (1130) a first linkbundle metric advertising decision, said first link bundle metricadvertising decision being a decision to: i) advertise the normal linkbundle metric for the first link bundle; ii) advertise the limitedoperation mode link bundle metric for the first link bundle; or iii)perform no advertising of a link bundle metric for the first linkbundle; and taking (1152) an advertising action in accordance with thedetermined first link bundle metric advertising decision, saidadvertising action including operating the first node to: i) advertise(1158) the normal link bundle metric for the first link bundle, ii)advertise (1162) the limited operation mode link bundle metric for thefirst link bundle or iii) control (1166) the first node to refrain fromadvertising a link bundle metric for the first link bundle.

Method Embodiment 2 The method of Method Embodiment 1, whereinadvertising (1158) the normal link bundle metric for the first linkbundle or advertising (1162) the limited operation mode link bundlemetric for the first link bundle includes operating (1160 or 1164) atransmitter in the first node to transmit the link bundle metric to beadvertised; and wherein controlling (1166) the first node to refrainfrom adverting a link bundle metric for the first link bundle includessetting (1168) a value in memory indicating that a link bundle metric isnot to be transmitted for the first link bundle.

Method Embodiment 3 The method of Method Embodiment 1, whereindetermining (1104) a normal link bundle metric for a first link bundleincluding a plurality of communications links between a first networknode and a second network node includes: receiving (1106) inputindicating a first normal link bundle metric corresponding to the firstlink bundle; and using (1108) the received first normal link bundlemetric as the determined normal link bundle metric for the first linkbundle.

Method Embodiment 4 The method of Method Embodiment 1 whereindetermining (1104) a normal link bundle metric for a first link bundleincludes: automatically generating (1110) the normal link bundle metricfor the first link bundle using an automated link weight generationalgorithm.

Method Embodiment 5 The method of Method Embodiment 4, wherein said stepof automatically generating (1110) the normal link bundle metric for thefirst link bundle includes using (1112) a link weight generationalgorithm to generate said normal link bundle metric for the first linkbundle.

Method Embodiment 6 The method of Method Embodiment 3, whereindetermining (1114) a limited operation mode link bundle metric for thefirst link bundle includes: receiving (1116) input indicating a firstlimited operation mode link bundle metric corresponding to the firstlink bundle; and using (1118) the received first limited operation modelink bundle metric as the determined limited operation mode link bundlemetric for the first link bundle.

Method Embodiment 7 The method of Method Embodiment 3, whereindetermining (1114) a limited operation mode link bundle metric for thefirst link bundle includes: setting (1120) the limited operation modelink bundle metric for the first link bundle to a maximum link metricvalue (e.g., set the metric to the largest permitted link weight valueto discourage its use where large values indicate links with longerpaths or which are more costly in this way causing the routing system toavoid use of the faulty link bundle unless there are no otheralternative links available since the path is indicated to be the mostcostly a path can be).

Method Embodiment 8 The method of Method Embodiment 3, whereindetermining (1114 or 1124) a limited operation mode link bundle metricfor the first link bundle includes: multiplying (1119 or 1126) the firstnormal link metric corresponding to the first link bundle by a costfactor greater than one to generate the limited operation mode linkbundle metric for the first link bundle.

Method Embodiment 9 The method of Method Embodiment 8, wherein said costfactor is a function of the current number of good links.

Method Embodiment 10 The method of Method Embodiment 9, furthercomprising: determining (1125) said cost factor as a function of thedetermined number of good links in the first link bundle.

Method Embodiment 11 The method of Method Embodiment 8, wherein the costfactor is larger when the number of good links in the first bundle isless than a first limited operation mode number of links than when thenumber of good links is equal to the first limited operation number oflinks.

Method Embodiment 12 The method of Method Embodiment 1, wherein making(1130) a first link bundle metric advertising decision includes:determining (1132) if a current number of good links in the first linkbundle is above a first limited operation mode number of links (whereabove the first limited operation mode number of links indicates thatthe first link bundle is operating in normal mode with all links or atleast a sufficient number of good links to support normal link bundlemode operation, e.g., with a sufficient number of links to support anormal expected traffic load).

Method Embodiment 13 The method of Method Embodiment 12, furthercomprising: prior to determining (1132) if a current number of goodlinks in the first link bundle is above a first limited operation modenumber of links, determining (1122) the number of good links in thefirst link bundle.

Method Embodiment 14 The method of Method Embodiment 12, wherein making(1130) a first link bundle metric advertising decision further includes:deciding (1136) to advertise the normal link bundle metric for the firstlink bundle in response to determining that a current number of goodlinks in the first link bundle is above a first limited operation modenumber of links.

Method Embodiment 15 The method of Method Embodiment 12, wherein making(1130) a first link bundle metric advertising decision further includes:determining (1138) if the current number of good links in the first linkbundle is a non-zero number of good links which is equal to or below thefirst limited operation mode number of links.

Method Embodiment 16 The method of Method Embodiment 15, wherein making(1130) a first link bundle metric advertising decision further includes:deciding (1142) to advertise the limited operation mode link bundlemetric for the first link bundle in response to determining that thecurrent number of good links in the first link bundle is a non-zeronumber of good links which is equal to or below the first limitedoperation mode number of links.

Method Embodiment 17 The method of Method Embodiment 15, wherein making(1130) a first link bundle metric advertising decision further includes:determining (1144) that the current number of good links in the firstlink bundle is zero; and deciding (1146) not to advertise the limitedoperation mode link bundle metric for the first link bundle in responseto determining that the current number of good links in the first linkbundle is zero. (When number of good links in first bundle is zero, nolinks metric will be advertised for the first bundle and thus deviceswill not consider using the first link bundle as a viable link whenmaking routing decisions based on advertised link metrics, e.g., linkweights which can be used for shortest path first, lowest cost pathrouting or other forms of link weight-based routing decisions).

Second Numbered List of Exemplary Embodiments

Apparatus Embodiment 1 A first network node (1200) in a communicationsnetwork (100), the first network node comprising: a processor (1202)configured to: determine (1104) a normal link bundle metric for a firstlink bundle including a plurality of communications links between afirst network node and a second network node; determine (1114 or 1124) alimited operation mode link bundle metric for the first link bundle;make (1130) a first link bundle metric advertising decision, said firstlink bundle metric advertising decision being a decision to: i)advertise the normal link bundle metric for the first link bundle; ii)advertise the limited operation mode link bundle metric for the firstlink bundle; or iii) perform no advertising of a link bundle metric forthe first link bundle; and control the first node to take (1152) anadvertising action in accordance with the determined first link bundlemetric advertising decision, said advertising action including operatingthe first node to: i) advertise (1158) the normal link bundle metric forthe first link bundle, ii) advertise (1162) the limited operation modelink bundle metric for the first link bundle or iii) control (1166) thefirst node to refrain from advertising a link bundle metric for thefirst link bundle.

Apparatus Embodiment 2 The first network node of Apparatus Embodiment 1,further including: a transmitter (1258); a memory (1212); and whereinadvertising (1158) the normal link bundle metric for the first linkbundle or advertising (1162) the limited operation mode link bundlemetric for the first link bundle includes operating (1160 or 1164) saidtransmitter in the first node to transmit the link bundle metric to beadvertised; and wherein controlling (1166) the first node to refrainfrom adverting a link bundle metric for the first link bundle includessetting (1168) a value in memory indicating that a link bundle metric isnot to be transmitted for the first link bundle.

Apparatus Embodiment 3 The first network node of Apparatus Embodiment 1,further comprising: a receiver (1246) configured to receive (1106) inputindicating a first normal link bundle metric corresponding to the firstlink bundle; and wherein the processor further configured as part ofdetermining (1104) a normal link bundle metric for a first link bundleincluding a plurality of communications links between a first networknode and a second network node to: use (1108) the received first normallink bundle metric as the determined normal link bundle metric for thefirst link bundle.

Apparatus Embodiment 4 The first network node of Apparatus Embodiment 1,wherein said processor is configured, as part of determining (1104) anormal link bundle metric for a first link bundle to: automaticallygenerating (1110) the normal link bundle metric for the first linkbundle using an automated link weight generation algorithm.

Apparatus Embodiment 5 The first network node of Apparatus Embodiment 4,wherein said processor, as part of automatically generating (1110) thenormal link bundle metric for the first link bundle, uses (1112) a linkweight generation algorithm to generate said normal link bundle metricfor the first link bundle.

Apparatus Embodiment 6 The first network node of Apparatus Embodiment 3,wherein the receiver is further configured to receive (1116) inputindicating a first limited operation mode link bundle metriccorresponding to the first link bundle; and wherein the processor isfurther configured as part of determining (1114) a limited operationmode link bundle metric for the first link bundle to: use (1118) thereceived first limited operation mode link bundle metric as thedetermined limited operation mode link bundle metric for the first linkbundle.

Apparatus Embodiment 7 The first network node of Apparatus Embodiment 3,wherein the processor is further configured, as part of determining(1114) a limited operation mode link bundle metric for the first linkbundle to: set (1120) the limited operation mode link bundle metric forthe first link bundle to a maximum link metric value (e.g., set themetric to the largest permitted link weight value to discourage its usewhere large values indicate links with longer paths or which are morecostly in this way causing the routing system to avoid use of the faultylink bundle unless there are no other alternative links available sincethe path is indicated to be the most costly a path can be).

Apparatus Embodiment 8 The first network node of Apparatus Embodiment 3,wherein said processor is further configured to multiply (1119 or 1126)the first normal link metric corresponding to the first link bundle by acost factor greater than one to generate the limited operation mode linkbundle metric for the first link bundle, as part of being configured todetermine (1114 or 1124) a limited operation mode link bundle metric forthe first link bundle.

Apparatus Embodiment 9 The first network node of Apparatus Embodiment 8,wherein said cost factor is a function of the current number of goodlinks.

Apparatus Embodiment 10 The first network node of Apparatus Embodiment9, wherein said processor is further configured to: determine (1125)said cost factor as a function of the determined number of good links inthe first link bundle.

Apparatus Embodiment 11 The first network node of Apparatus Embodiment8, wherein the cost factor is larger when the number of good links inthe first bundle is less than a first limited operation mode number oflinks than when the number of good links is equal to the first limitedoperation number of links.

Apparatus Embodiment 12 The first network node of Apparatus Embodiment1, wherein said processor is further configured to: determine (1132) ifa current number of good links in the first link bundle is above a firstlimited operation mode number of links, as part of being configured tomake (1130) a first link bundle metric advertising decision. (Whereabove the first limited operation mode number of links indicates thatthe first link bundle is operating in normal mode with all links or atleast a sufficient number of good links to support normal link bundlemode operation, e.g., with a sufficient number of links to support anormal expected traffic load).

Apparatus Embodiment 13 The first network node of Apparatus Embodiment12, wherein said processor is further configured to: determine (1122)the number of good links in the first link bundle, prior to determining(1132) if a current number of good links in the first link bundle isabove a first limited operation mode number of links.

Apparatus Embodiment 14 The first network node of Apparatus Embodiment12, wherein said processor is further configured to decide (1136) toadvertise the normal link bundle metric for the first link bundle inresponse to determining that a current number of good links in the firstlink bundle is above a first limited operation mode number of links, aspart of being configured to make (1130) a first link bundle metricadvertising decision.

Apparatus Embodiment 15 The first network node of Apparatus Embodiment12, wherein said processor is further configured to determine (1138) ifthe current number of good links in the first link bundle is a non-zeronumber of good links which is equal to or below the first limitedoperation mode number of links, as part of being configured to make(1130) a first link bundle metric advertising decision.

Apparatus Embodiment 16 The first network node of Apparatus Embodiment15, wherein said processor is further configured to decide (1142) toadvertise the limited operation mode link bundle metric for the firstlink bundle in response to determining that the current number of goodlinks in the first link bundle is a non-zero number of good links whichis equal to or below the first limited operation mode number of links,as part of being configured to make (1130) a first link bundle metricadvertising decision.

Apparatus Embodiment 17 The first network node of Apparatus Embodiment15, wherein said processor is further configured to: determine (1144)that the current number of good links in the first link bundle is zero;and decide (1146) not to advertise the limited operation mode linkbundle metric for the first link bundle in response to determining thatthe current number of good links in the first link bundle is zero, saidbeing configured to determine and decide being part of being configuredto make (1130) a first link bundle metric advertising decision. (whennumber of good links in first bundle is zero, no links metric will beadvertised for the first bundle and thus devices will not consider usingthe first link bundle as a viable link when making routing decisionsbased on advertised link metrics, e.g., link weights which can be usedfor shortest path first, lowest cost path routing or other forms of linkweight-based routing decisions).

Third Number Set of Exemplary Embodiments

Computer Readable Medium Embodiment 1 A non-transitory computer readablemedium (1212) including computer executable instructions which whenexecuted by a processor (1202) of a first network node (1200) cause thefirst network node (1200) to perform the steps of: determining (1104) anormal link bundle metric for a first link bundle including a pluralityof communications links between a first network node and a secondnetwork node; determining (1114 or 1124) a limited operation mode linkbundle metric for the first link bundle; making (1130) a first linkbundle metric advertising decision, said first link bundle metricadvertising decision being a decision to: i) advertise the normal linkbundle metric for the first link bundle; ii) advertise the limitedoperation mode link bundle metric for the first link bundle; or iii)perform no advertising of a link bundle metric for the first linkbundle; and taking (1152) an advertising action in accordance with thedetermined first link bundle metric advertising decision, saidadvertising action including operating the first node to: i) advertisethe normal link bundle metric for the first link bundle, ii) advertisethe limited operation mode link bundle metric for the first link bundleor iii) control the first node to refrain from advertising a link bundlemetric for the first link bundle.

The techniques of various embodiments may be implemented using software,hardware and/or a combination of software and hardware. Variousembodiments are directed to apparatus, e.g., routers, network nodes,user devices, base stations, servers, customer premises equipmentdevices, cable systems, network nodes, gateways, cable headend/hubsites,network monitoring node/servers, cluster controllers, cloud nodes,production nodes, cloud services servers and/or network equipmentdevices. Various embodiments are also directed to methods, e.g., methodof controlling and/or operating routers, network nodes, user devices,base stations, gateways, servers, cable networks, cloud networks, nodes,servers, cloud service servers, customer premises equipment devices,controllers, network monitoring nodes/servers and/or cable or networkequipment devices. Various embodiments are also directed to machine,e.g., computer, readable medium, e.g., ROM, RAM, CDs, hard discs, etc.,which include machine readable instructions for controlling a machine toimplement one or more steps of a method. The computer readable mediumis, e.g., non-transitory computer readable medium.

It is understood that the specific order or hierarchy of steps in theprocesses and methods disclosed is an example of exemplary approaches.Based upon design preferences, it is understood that the specific orderor hierarchy of steps in the processes and methods may be rearrangedwhile remaining within the scope of the present disclosure. Theaccompanying method claims present elements of the various steps in asample order, and are not meant to be limited to the specific order orhierarchy presented. In some embodiments, one or more processors areused to carry out one or more steps of the each of the describedmethods.

In various embodiments each of the steps or elements of a method areimplemented using one or more processors. In some embodiments, each ofelements are steps are implemented using hardware circuitry.

In various embodiments nodes and/or elements described herein areimplemented using one or more components to perform the stepscorresponding to one or more methods, for example, message reception,signal processing, sending, comparing, determining and/or transmissionsteps. Thus, in some embodiments various features are implemented usingcomponents or in some embodiments logic such as for example logiccircuits. Such components may be implemented using software, hardware ora combination of software and hardware. Many of the above describedmethods or method steps can be implemented using machine executableinstructions, such as software, included in a machine readable mediumsuch as a memory device, e.g., RAM, floppy disk, etc. to control amachine, e.g., general purpose computer with or without additionalhardware, to implement all or portions of the above described methods,e.g., in one or more nodes. Accordingly, among other things, variousembodiments are directed to a machine-readable medium, e.g., anon-transitory computer readable medium, including machine executableinstructions for causing a machine, e.g., processor and associatedhardware, to perform one or more of the steps of the above-describedmethod(s). Some embodiments are directed to a device, e.g., acontroller, including a processor configured to implement one, multipleor all of the steps of one or more methods of the invention.

In some embodiments, the processor or processors, e.g., CPUs, of one ormore devices, e.g., communications nodes such as controllers areconfigured to perform the steps of the methods described as beingperformed by the communications nodes, e.g., controllers. Theconfiguration of the processor may be achieved by using one or morecomponents, e.g., software components, to control processorconfiguration and/or by including hardware in the processor, e.g.,hardware components, to perform the recited steps and/or controlprocessor configuration. Accordingly, some but not all embodiments aredirected to a device, e.g., communications node such as a clustercontroller including, with a processor which includes a componentcorresponding to each of the steps of the various described methodsperformed by the device in which the processor is included. In some butnot all embodiments a device, e.g., communications node such as acontroller, includes a controller corresponding to each of the steps ofthe various described methods performed by the device in which theprocessor is included. The components may be implemented using softwareand/or hardware.

Some embodiments are directed to a computer program product comprising acomputer-readable medium, e.g., a non-transitory computer-readablemedium, comprising code for causing a computer, or multiple computers,to implement various functions, steps, acts and/or operations, e.g. oneor more steps described above. Depending on the embodiment, the computerprogram product can, and sometimes does, include different code for eachstep to be performed. Thus, the computer program product may, andsometimes does, include code for each individual step of a method, e.g.,a method of controlling a controller or node. The code may be in theform of machine, e.g., computer, executable instructions stored on acomputer-readable medium, e.g., a non-transitory computer-readablemedium, such as a RAM (Random Access Memory), ROM (Read Only Memory) orother type of storage device. In addition to being directed to acomputer program product, some embodiments are directed to a processorconfigured to implement one or more of the various functions, steps,acts and/or operations of one or more methods described above.Accordingly, some embodiments are directed to a processor, e.g., CPU,configured to implement some or all of the steps of the methodsdescribed herein. The processor may be for use in, e.g., acommunications device such as a router, a controller or other devicedescribed in the present application. In some embodiments components areimplemented as hardware devices in such embodiments the components arehardware components. In other embodiments components may be implementedas software, e.g., a set of processor or computer executableinstructions. Depending on the embodiment the components maybe allhardware components, all software components, a combination of hardwareand/or software or in some embodiments some components are hardwarecomponents while other components are software components.

Numerous additional variations on the methods and apparatus of thevarious embodiments described above will be apparent to those skilled inthe art in view of the above description. Such variations are to beconsidered within the scope. Numerous additional embodiments, within thescope of the present invention, will be apparent to those of ordinaryskill in the art in view of the above description and the claims whichfollow. Such variations are to be considered within the scope of theinvention.

What is claimed is:
 1. A method of operating a first network node in acommunications network, the method comprising: determining a number ofoperational links in a first link bundle including a failed link;comparing the number of operational links in the first link bundle to afirst limited operation mode number of links to determine whether thenumber of operational links exceeds said first limited operation modenumber of links, said first limited operation mode number of links beinga non-zero number; making a first link bundle metric advertisingdecision based on said determination of whether the number ofoperational links exceeds said first limited operation mode number oflinks; wherein said first link bundle metric advertising decision is adecision to advertise a normal link bundle metric for the first linkbundle when the number of operational links in the first link bundleexceeds the first limited operation mode number of links; and whereinfirst link bundle metric advertising decision is a decision to i)advertise a limited operation mode link bundle metric for the first linkbundle or ii) refrain from advertising a link bundle metric for thefirst link bundle when the number of operational links in the first linkbundle is determined not to exceed the first limited operation modenumber of links.
 2. The method of claim 1, wherein the first limitedoperation mode number of links is a non-zero positive number.
 3. Themethod of claim 2, wherein the first limited operation mode number oflinks is
 3. 4. The method of claim 1, further comprising: setting thelimited operation mode link bundle metric for the first link bundle to amaximum link metric value.
 5. The method of claim 1, further comprising:advertising a normal link bundle metric for the first link bundleincluding the failed link in response to determining that the number ofoperational links exceeds said first limited operation mode number oflinks.
 6. The method of claim 2, wherein first link bundle metricadvertising decision is a decision to advertise the limited operationmode link bundle metric for the first link bundle when the number ofoperational links is a non-zero number equal to or below said firstlimited operation mode number of links.
 7. The method of claim 2,wherein first link bundle metric advertising decision is a decision torefrain from advertising a link bundle metric for the first link bundlewhen the number of operational links in the first link bundle isdetermined to be zero.
 8. The method of claim 1, wherein the first linkbundle is a bundle of Ethernet links.
 9. The method of claim 2, whereinthe first link bundle is a bundle of Ethernet links.
 10. The method ofclaim 1, further comprising: automatically generating the normal linkbundle metric for the first link bundle using an automated link weightgeneration algorithm.
 11. A network node in a communications network,comprising: a transmitter; a memory; and a processor configured to:determine a number of operational links in a first link bundle includinga failed link; compare the number of operational links in the first linkbundle to a first limited operation mode number of links to determinewhether the number of operational links exceeds said first limitedoperation mode number of links, said first limited operation mode numberof links being a non-zero number; make a first link bundle metricadvertising decision based on said determination of whether the numberof operational links exceeds said first limited operation mode number oflinks; wherein said first link bundle metric advertising decision is adecision to advertise a normal link bundle metric for the first linkbundle when the number of operational links in the first link bundleexceeds the first limited operation mode number of links; and whereinfirst link bundle metric advertising decision is a decision to i)advertise a limited operation mode link bundle metric for the first linkbundle or ii) refrain from advertising a link bundle metric for thefirst link bundle when the number of operational links in the first linkbundle is determined not to exceed the first limited operation modenumber of links; and control the network node to implement the firstlink bundle metric advertising decision.
 12. The network node of claim11, wherein the first limited operation mode number of links is anon-zero positive number.
 13. The network node of claim 12, wherein thefirst limited operation mode number of links is
 3. 14. The network nodeof claim 11, wherein the processor is further configured to control thenetwork node to: set the limited operation mode link bundle metric forthe first link bundle to a maximum link metric value.
 15. The networknode of claim 1, wherein the processor is further configured to controlthe network node to: advertise a normal link bundle metric for the firstlink bundle including the failed link in response to determining thatthe number of operational links exceeds said first limited operationmode number of links.
 16. The network node of claim 12, wherein firstlink bundle metric advertising decision is a decision to advertise thelimited operation mode link bundle metric for the first link bundle whenthe number of operational links is a non-zero number equal to or belowsaid first limited operation mode number of links.
 17. The network nodeof claim 12, wherein first link bundle metric advertising decision is adecision to refrain from advertising a link bundle metric for the firstlink bundle when the number of operational links in the first linkbundle is determined to be zero.
 18. The network node of claim 11,wherein the first link bundle is a bundle of Ethernet links.
 19. Thenetwork node of claim 12, wherein the first link bundle is a bundle ofEthernet links.
 20. The network node of claim 19, wherein the processoris further configured to control the network node to: automaticallygenerate the normal link bundle metric for the first link bundle usingan automated link weight generation algorithm.